I Can't stand on my legs I am getting trouble in walking after 50 sit ups, after that tried to climb stairs, my knees are over bending, then I am unable to climb stairs for a while, this all happened in my college, after my college is over ,I tried to walk, then my knees are still bending, but effect is decreased compared to walk after sit-ups, so then I walked carefully, it took 1 week to get normal, I am a male then i was 17, now I am 20 ,once I arm wrestled with my friend, and I won it with a great effort, then my hand got stiffen and swelled after I won and remained same for 30 mins approximately, once I tried viagra Asana (yoga pose) on floor with out any kind of soft mats, after 15 mins, I was unable to feel my legs, then suddenly I feared and lied down normally, after 5 or 10 mins my legs became normal, I have forget full ness ,weak memory also, please doctor tell me about my condition.