Pain in the right leg that goes and goes, sometimes on the side, sometimes in the groin. burns behind the knee and gets worse with cold. what can be?

Bursitis v. tendon: Your symptoms could describe bursitis (inflammation of the bursal fat pad underneath many tendon insertions) or tendonitis (inflammation of the tendon itself. Both stem from extreme use/overuse of the affected area. Inflammation is the pathological process. After 5-10 days of NSAID therapy (e.g. ibuprofen 600-800mg three to four times per day), if no better, see an orthopedist.