 [ Symptoms ] i have pain in the back of my left knee after walking for a while i get an excrutiating pain to where i have to limp after walking for about 30 minutes or standing long periods or driving a long distance i get a pain in the back of my left knee crease that feels like i cant straighten my leg out so i have to limp this also includes a burning sensation above the pain in my thigh eventually i can mange to walk on it but it does not go a way unless i sit for a while i have taken motrin since i know it helps with inflamation i also can not bend my leg all the way back because of the pain [ Disease ] i am sorry to hear you are going through this here you are exercising like doctors tell us to and then you have an uncomfortable problem occur it seems a little unfair does not it i am going to recommend you see a doctor about this while several things could cause the symptoms you describe    and i am not a medical doctor myself    your situation sounds an awful lot like it could be a baker is cyst a doctor could tell you for sure baker is cysts are not cancerous or life threatening in any way but they sure can interfere with exercise    and even with activities of daily living your doctor can suggest ways to treat the cyst on your own and if those do not work he or she can perform a small procedure to drain the cyst of course your knee problems could have many other causes such as tendinitis and arthritis your doctor can diagnose the issue with a physical examination and possibly an x ray wishing you well