I have a sore muscle in my thigh above my knee. it is tender to the touch & sore when walking. aches at times when sitting.any concern of blood clot?

Exam needed: Any new redness, swelling on an extremity should be examined by your doctor. If it appears deep, large, painful to touch, prompt Emergency Room care is what I would recommend. If it is superficial like a pimple / infection it would still require an assessment. Good luck.

Blood clots: Usually the risk of blood clots depends on where the pain and swelling is in the leg. Pain in the inner or posterior leg with redness is more likely to be a blood clot. In your case the major factor is that you take birth control pills. I am sure you were told at the start that these increase the risk of blood clots. Especially in smokers. Better get this checked soon.

Probably not: Blood clots usually form in the deep vessels of the leg. They can cause pain behind the knee and they often cause leg and ankle swelling. It sounds like you have a muscle strain, not a blood clot. Birth control pills do increase the risk for blood clots so it is important to stay active and not smoke. If you have swelling in one leg/ankle then it is a good idea to see a doctor.