Painful pop in my hamstring, but not sure what the injury is

Hello all,
I’m a 24 year old man. I was sumo deadlifting a 1 rep max about 3 weeks and 1 day ago. As I was halfway up, I felt/heard a pop in my hamstring. I felt the pain was about halfway between my buttocks and knee. There was no bruising. For the first few days, if I walked and engaged that part of my hamstring, I would be in pain. Now, the pain has faded away. I can press down on (I think the biceps femoris?) and feel a tender spot there it ‘popped’. However, I do feel tightness in my calf sometimes, and one of my tendons is still giving me pain and irritation. Its the tendon on the left side of my left knee. If I flex, I can feel that its the tendon that comes directly from the muscle I popped. Is this a side effect of a hamstring muscle belly strain? is this a hamstring tendon strain? What can I do to rehab it, and once I’ve rehabbed it make sure it never happens again?

With regards to rehab, I’ve been doing light banded good mornings and light sumo deadlifts (maybe 25% of my max) and it feels like it helps but that could be a placebo. I have been eating oily fish, lots of protein, and collagen to help recover from this.

Sounds like a muscle strain. This is discussed here:

Thanks Austin. I was worried it was a tendon issue, how did you rule it out?

Also, since it’s been 3 weeks. I haven’t had a consistent rehab plan until you gave me that, so should I be massaging the strain to help with scar tissue?

Lastly, is regular upper body training fine? I figure by now things like the overhead press should be fine, but I don’t know if I should be stretching my hamstrings even now during pendlay rows.

Update now that it’s been 4 weeks since my injury: I did nordic ham curls one day and glute ham raises another, supplemented by lying hamstring curls. I’ve found the tenderness in the muscle is subsiding. However, I feel this kind of tightness or even a bit of inflammation or pain downstream from the original injury point. Its mostly in the side tendon of the back left of the knee, and sometimes my calf and ankle get tight too. Pain increases when I turn my left foot outwards. Is this normal with a muscle strain?

Yes, that is normal. It will typically take some time to regain full strength in that leg.

3 months after injury: I still get the outermost tendon under my knee, one of the two ‘strings’ at the back of my knee, inflamed every now and then. It seems to happen with as simple as flexing that tendon a lot. I can do things like pendlay rows without pain or inflammation though as long as i dont flex that tendon. Really its just inflammation not pain, but that still worries me. I did a set of good mornings at a working weight last weeknand it inflames easier.

Should I avoid squatting or anything that inflames it? What can I do to make this go away, and how long must I wait before it does?

edit: After reading the article on tendinopathy here: https://www.barbellmedicine.com/blog/the-barbell-medicine-guide-to-tendinopathy/ - I realize I am probably in the same boat. Does anyone have any specific recommendations for my case with the outermost lower hamstring tendon?