I am a 30yr female. When I sit down or lay down my right thigh from above the knee up goes completely dead. I dont get pins and needles like one would if it was a circulation issue. If it remains that way for any length of time I'll get burning sensations and on occasion a horrid stabbing feeling. While standing its not so bad. Once in a while I'll get an itching sensation but the right half of the thigh will still be numb. So far I've tried ibuprofen. What might be causing this. Not sure if its important but I've two knee surgeries on that leg and a small portion of the knee area has always been kinda numb even though they said I should have no nerve damage.