Hey!
Sorry to hear about your issues.
Sounds like it could be the biceps femoris acting up. Are you feeling anything on the inside or just the outside? Have you checked your lower back? Considering you’re having problems both when you activate it (walking/running) and when you’re resting it, we might be dealing with some type of impingement process in the lower back that’s causing the hamstrings to tighten up and become irritated.
Any numbness/tingling or sharp/shooting pains down the legs?
/Eric
www.nordicathletics.se