Pain in the side of right knee since 1yr

I was doing side lunge, i heard a popping sound in the knee and the pain started. I consulted a doctor he told me to do mri because he thought it could be meniscus tear, but mri showed there's minor water effusion, so he told me to rest and not to bend my knee more than 90°, now the knee doesn't pain every time, it pains when i start my workout like running and skipping rope, then i consulted again and he told me to do xray of both the knee to check the alignments and xray was normal, i also did cbc and uric acid test that was also normal. And then i did esr test that wasn't normal because esr should be under 14%but mine it was 41%.(i have uploaded my test reports pls check) My doc says its normal and gave me calcium and vitamin tablets. But still i dont know why my leg is paining, where the prob is?