As soon as I stood up from a 2.5 hr. flight I experienced sharp pain in my upper left thigh. Because the woman on my left & I talked most of the flight I assumed I just sat wrong. Now, 2 days later I'm still suffering with that pain & have difficulty walking from a sitting position. What should I do?

Please go to your doctor to be evaluated for a deep vein thrombosis.

Sounds like a DVT, deep vein thrombosis which is a blood clot. These can travel so get into your doctor or the ER. If it is they may put you on a heparin drip to thin out the blood and break down the clot but this can be serious and potentially life threatening.