Outer knee pain while running

I’ve been dealing with outer knee pain on both knees while playing sports (soccer or any running) for more than 2 months. I also lift weights at home but have no pain doing it. It all started after I had finished playing soccer for 90 min. I could barely walk that day up stairs or down stairs (way less pain when walking normally tho). The day after when I woke up, the pain got away and I could walk normally again. I rested for a week or two and again tried playing soccer. I could play for like 30 min before starting to feel the same problem again – pain in the outer knee. The movements where you change directions quick or fast accelerations/decelerations were very painful. A few days later I started doing some research on it and suspected that I had iliotibial band syndrome. I found a few exercises which might help and did them for a few weeks. After resting and doing the exercises I tried playing playing again. This time, I felt the same pain even eariler – after running for like 2 minutes. Whenever I play and go through the pain, I can barely walk up or down hill after and the pain diminishes the next day. My doctor has recently prescribed me medication (Nalgesin forte) which I have to take for 10 straight days, but I doubt that will solve the problem.