Knee pain on left side, under knee cap to the touch. the knee is tight and hurts to bend. especially going down stairs. it is swollen above knee cap.

Go see PCP: Your symptoms of pain, swelling, tenderness, and decreased range of motion are suggestive of inflammation. It can be as benign as a tendinitis if you recently did some strenuous exercising, or more serious if you are having fevers (it can be sign of infection or gout).

Needs Medical examin: Your knee may have been hurt recently. Did you fall or injure your knee in someway? It appears that there is fluid accumulation in the knee joint. This will require a visit with an Orthopedic specialist for examination, Imaging X-rays and an appropriate treatment