Pain in the back of my knee

I'm a 31 year old male and I had a meniscus tear about 4 or 5 years ago on my right knee. (The pain then was down side and back of knee.) there was also a cyst which had developed. I ended up having surgery but the tears were that bad that they couldn't be completely repaired. The pain at its worst then was a about a 9 and it started to really burn at times. It got to the point where I couldn't walk on it. I'm not exactly sure how long I was walking on it before I made it worse.

Since the initial surgery I have been ok enough to walk briskly and quite vigorously but never been able to run or anything like that. I should add thati aka postman so walk quite intensely all week.

Just the other day I stupidly ran quite intensely in the back garden with my little boy and I feel I have done something again. At the minute the pain seems to be quite mild and is mainly at the back of my knee, towards the right side, More where the tendon/ligament seems to be. I remember a similar feeling at times before my initial surgey years ago. At the minute I can still walk on it but I have to be quite careful and don't feel I can twist and turn on it or it will just go or become more painful. It also seems more painful when I'm driving or my legs bent. I don't really know what I have done but I just hoping I don't need surgery again or it gets worse as I can't afford to take time off work. I did this last Wednesday.

I have hopefully attached a picture to give an idea of where exactly the pain is currently.

If if anyone has any advice on whether physio would help or what it's likely to be I would be very grateful. I have also noticed that I over pronate significantly and I'm not sure whether this is causing any more harm. I'm looking into getting some specially designed insoles.