Four weeks ago I took an airplane ride from Jacksonville FL to Seattle WA with a short layover in Denver. I wore compression socks that I think were too tight. When I arrived in Seattle. I took the socks off and noticed a red welt line around the top of my calf, as well as I had (STILL HAVE) pain at the top of my calf behind my knee. For the next three weeks I was on a bus tour of the Rockie Mountain National Parks from Colorado to Canada and was often sitting for extended periods of time. When we did stop it was for meals and I continued to sit. I went to the doctor this week ( I had been home for five days) to talk to him about my concern that I could be developing a blood clot. He measured my leg, noted there was no swelling, placed his thumbs along my leg to determine if he could feel anything, and told me that if my leg got hot, began swelling, developed a red rash, or the pain moved to come back. I take a blood thinner because I had a TIA three years ago and am hopeful that helps lessen the possibility of a blood clot. What else besides a blood clot would cause so much discomfort? Generally the pain is only when I walk and even then not all of the time.