Is this posterior tibial tendinitis

Do you have flat feet and are you going minimalist and-or zero drop? PT tendon points your foot down and in. See if that hurts. Runs right behind the ankle bone and into the arch on the inside arch.

I have a medium arch. Maybe high if anything

and I wear Nike Pegasus most recently with endorphin speeds for workouts and long runs

been running in neutral shoes for a bit but have been mixing up over years. Favorites were the old bostons

That does sound like PTT. I had that and was running on it unknowing for a long time. In pain. I was also an overpronator with flat feet. By the time I went to the podiatrist it was at a very advanced stage and would have completely torn in the near future. I had to have surgery. First to set my foot into neutral position (overpronating was a contributor to PTT) and then to sew up the tendon. Long recovery but that was many years ago and I have been running now with zero issues

Is it the most stiff / painful first thing getting out of bed in the morning?

Fairly uncommon in non pronators. Get it checked, easy diagnosis in person. This is one issue that orthotics work well for.

doesn’t hurt more in morning. Feels fine when I walk and just sit and whatever throughout day

was just hurting on a few runs. First few times it went away after a mile or two. Then had a run where it didn’t go away and hurt a bit more so I took a few days off. Ran Monday and had slight pain but not major and was less than was before

What type of specialist would I go to for a check on it?

This is what PT's use to diagnose PTTD.

Sewed up even though it wasn't torn?

Probably a bit of irritation/inflammation in your PTT. Not a huge deal if you act now to strengthen the tendon and muscles and it doesn't become chronic tendinopathy. If it usually goes away after a few miles I wouldn't bother going to see a PT or specialist - it usually costs $$ and they'll pressure you to keep coming in. I would start doing these things religiously, on both left and right:

Get some kind of band (even a bike inner tube would work) and start doing lots of inversion exercises. I find it works best to wrap the band around a heavy table or chair leg and sit with your leg straight so you can maximize the force you can put into the band. Sometimes people recommend wrapping the band around your other leg or something but that doesn't work nearly as well if your posterior tibialis is already strong since you need lots of leverage to maximize the load (and since you're a runner and have medium/high arches, your PT muscle is probably stronger already than 99% of people). Do this slowly and controlled until your PT muscle is tired, every day. This helps strengthen that PT muscle specifically and also loads the tendon without major impact force, which will help it to heal.

You mentioned calf raises don't hurt, which is good. I recommend doing lots of eccentric calf raises on a stair, making sure to keep your PT muscle engaged and your arch high. Maintain strong contact with the stair in your big toe bone to make sure the PT muscle is engaged throughout the slow, downward motion. Eccentric loading is gentle but therapeutic for the tendon. This will also help strengthen your soleus which is beneficial.

Single leg balance for as long as you can hold without pain and feeling strong. You could get a balance pad or similar to make this more difficult, but just doing it on the floor is also good as you can feel the way your feet are connecting to the ground. Try hard to keep your arch high and PT muscle engaged the whole time.

I recommend doing all of these things immediately prior to running to "wake up" your posterior tibialis and soleus and warm up the tendon. You might find that this decreases the amount of pain you feel at the start of runs. Good luck!

Pain on the inside of the ankle, underneath the bone (medial malleolus) that sticks out? Sounds like PTT. Get checked by an orthopedic foot/ankle specialist to be sure.

I had PTT and it kept flaring up, going away and returning, after breaks away from running. It knocked me out of running completely for two years in my mid 40s. Finally, after some yoga, ankle physical therapy (at home on my own) and a cortisone shot, it got better. Now I've been running on it daily for 2 years and it's fine.

If I do a hard workout, it's slightly sore sometimes. Then it goes away after a recovery run the next day, or with occasional stretching and doing the resistance bands.

It's fixable. Get it fixed.

Good advice. Will definitely try these out and see if helps

dont think it’s full on PTT because of where I am with it right now but want to see what I can do to improve without stopping running altogether

would changing up shoes be something I should consider? I just got a new pair of pegs as previous had 350 miles on them but maybe I want something different altogether

Yes. It was at stage 3 out of 4. The tendon was torn but not all the way through and was able to be repaired. The more extreme procedure which I didn’t need is a graft or tendon transfer

Thanks. This helps since I'm currently going on 2 months with this injury. I actually haven't ran in 2 months and the pain is about the same as the first week. I have an appointment with a foot and ankle doc next week. Was your tear determined by MRI or other?

Yes. MRI was used

Thanks.

Yes. An MRI was done

You could go to your local running store and try some stability shoes and see how they feel. If they feel good you could try that for awhile. They should theoretically decrease the strain on the tendon slightly. But if you've been running in pegs for awhile and haven't had issues until now, I would stick with them. The downside with stability shoes and orthotics/inserts if you don't need them is that overtime they tend to weaken the muscles in your feet and ankle since they don't have to work as hard, but if you're doing lots of strengthening work barefoot then that shouldn't be a problem.