My knee pain started over a year ago, at that time i was doing a lot of excercise, got an x ray, looks normal and the pain is worse in hot weather?

Knee pain: Knee pain with a normal X-ray can be due to a variety of issues; the weather really should have no significant effect though. In your age group, overuse can cause joint inflammation, local tendonitis, etc. You can injure the soft tissues in your knee (e.g. meniscus tear, often with twisting motions) and these can take time to repair or need surgery if they are large enough. An MRI can help dx.