Shin splints from hell!

Man, I feel your pain.

Do your shoes show evidence of heavy heel striking? If so transition to midfoot/forefoot. Lay off the speed work.

Crosstrain our way out of it. Diagonal stride X-C skiing worked for me.

There's been a ton of good advice tendered in earlier threads on this syndrome. A search is in order.

Stand and put your toes over 90-degrees wide apart and heels together. Do lots of toe raises. Then put your toes together and heels apart (also at a fairly wide angle) and do more toe raises.

Also get some deep tissue massage work done on the hollow point (shaft-like length of muscle, actually) along the inside of your shin, there may be some muscle adhesion to the bone going on there. If there is it will feel lumpy in the painful spot. It's not too unusual but over time if that continues it can demineralize the bone and potentially lead to stress fractures.

Switch to racing flats or a shoe that has a minimal heel (platform) to toe downslope (10 mm or less). Older model shoes were superior in the sense they did not have an extra 10 mm. of air-gel, etc., which throw off alignment and mechanics. Shin splints and especially plantar fasciitis were rather uncommon ailments 25 years ago. Modern tech shoes weaken the feet and have caused a number of problems.