There is an incredibly annoying pain that has been present in the back of my knee for several months now. It began as a serious injury, but later nearly disappeared until recently. I cannot determine whether the pain is upper calf, lower hamstring, or perhaps ligament damage in the knee. I first noticed this when I was doing lying hamstring curls using my other foot as resistance. The pain then became noticeable running inclines and declines, going up and down stairs, stomping the affected leg (left) into the ground, standing on my toes, pushing the affected leg downwards while flexing the quads and hamstrings, rowing on a rowing machine, and running fast. I will occasionally feel snapping/shifting sensations in the injured region. Sorry about how overwhelming this is, but I am desperate to fix this. It began as a strong enough pain to warrant some time off running, but I am now able to run without it bothering me too much. Does anybody know what this could be and what I can do to help heal it? I do regular strength work and stretch/foam roll a good amount. I'm going to start using methods such as ice, heat, and compression to assist in recovery. Anything helps, thanks in advance.