Here’s a simple nerve or muscle test .
https://www.google.com/amp/s/www.orthocorept.com/blog/2018/7/24/is-it-sciatica-or-is-it-a-hamstring-strain%3fformat=amp
I get lower hamstring tendinitis about once a year, due to my sciatic nerve. I didn’t treat it at all the first time I got it and recovery took about four weeks.
The last two times I’ve treated it really well, it took 1-2 weeks to resolve. I’m not sure what exactly helped but here’s what I do:
Dry needling on the lower hamstring.
Putting a lacrosse ball on a chair, putting my hamstring on it and doing slow leg extensions, several times throughout the day
Nerve flossing throughout the day
Scrapping it a couple of minutes a day with an istym tool
Pool running. The times I hammered a pool workout, my hamstring would always feel better the next day. Movement and blood flow with slight to no inflammation is great for healing
I also did some hamstring rehab...nordics, eccentric hamstring curls, etc.
When it was runnable, I’d stick to the treadmill and run on a 3% or greater incline. This takes additional load off the hamstring. As it got better, I returned to flat running and stayed away from downhills.