My pants are getting tighter around my left upper thigh (labral tear location). it isn't very muscular & a bit fatty. is this just fat or swelling?

Leg swelling: 18 year old lady w/ swelling of the left upper thigh when compared with the right leg. Leg swelling that is unilateral should be evaluated for DVT, vascular problems including May-Thurner syndrome, cellulitis, ruptured Baker's cyst, fracture, compartment syndrome, and one of the most dangerous causes: bleeding. If you had significant trauma to your l leg see MD emergently. Otherwise see promptly.