Piriformis???

Please Help....I have been having this lower back pain and leg pain for over 3years now. The lower back pain has stopped. But the last year I have been having this leg type pain which is hard to identify. Whenever I put weight on the one leg it gives me this sharp pain inside the leg. Not all the time though. Just certain weird movements will aggravate this sharp pain down the leg. It seems to switch from right leg to left leg. Just the other day. After sitting on the computer....I try getting up and one leg I can't put any weight on it without having this sharp pain down the leg. I have tried many things. chiropractor for 3years...back inverter, etc. The best way I can describe it is: Certain bending movements is hard to get up. So, if anyone can please advise and help. I would really appreciate anything. Thanks in advance