Hamstring Tendonitis?

I ran a hard/fast 400m workout and felt tired but fine afterwards.

The next day at work my left hamstring was feeling very sore/cramped and achy but not strained at all. Went to practice the day after that and did 4x60m but was feeling the cramped hamstring at the end of each run so stopped.

My hamstring still feels like its swollen or something and its been 4 days now. Im thinking this isn’t a big thing as I was able to do full out 60s on it but im starting to get worried. The swelling/aching is in the belly of the hamstring and I was thinking maybe it is tendonitis but apparently that happens at the top of the hamstring or behind the knee.

any ideas?

Thanks!

Thats right - tendonitis has to occur on a tendon, which is found primarily at the top at bottom of the hamstring muscle.