Hamstring Concerns after recovery

OK so here’s the story, I had a level 2 (partial tear) hamstring pull in february during a 55 meter race (heard the pop and everything, went down like a brick). The place that I did it I can only describe is where the hamstring, hip and butt meet. There was no black and blue just a good amount of swelling. After I injured it, I went to PT until about april, getting deep tissue massages and different other things. I ended up starting to run again once I got out of therepy.
About 3 practices in I hear another pop, but this one wasn’t as bad and the swelling wasn’t as intesnse as t he one before. So after this injury I go to PT again so that I can get back to health by the end of the season. I end up going to PT until about May. At this point, I am not sprinting anymore I am doing the 4x800 (heh don’t ask, somehow a tried and true sprinter can somehow be a top 4 800 runner for a team.). I was doing some runs from that time on but every once in a while I’d have these sharp pains in my hamstring, they didn’t feel like strains or pulls, just pain, but it would really hamper me and forcing me to pull out of a few races. Because of that, I ended my season all together. ended up resting from about the end of my all the way to about 1 week into July, when I got my scheduale for college running from my coach. The workouts usually consist of 25-35 minute runs, 35-45 minute runs, intervals of 200, 300, 400’s at slow speeds (about 31 for 200, 49 for 300, and 68 for 400.)
My wonder is that, during all this time, I have not had any real problems with my hamstring it’s just that sometimes during runs, after runs, or just randomly throughout the day, I would have a really dull pain at about the same spot of my injury, nothing that will stop me from doing anything, just a little annoying (It should be noted that I do not have any tightness or lack of mobility in my hamsting.) Could it be that it is because I am just building up my bad hamstrings strength up again and it’s jsut pain from the work that I’m putting it through, (Before I started running again in July, there was a very noticebale difference in the size of my injured hamstring to my health hamstring), or that It’s somehow the scar tissue breaking up, or do I still have some kind of injury to it that will need to be tended when I get to college? Or, could it be all in my head since I am afraid to injure it again. Thank you guys for any response or any feedback you have.