The symptoms of the blood clot as you know are in the calf. There can be swelling, warmth, pain, tenderness, redness in the calf and ankle. When the blood clot moves from the calf to thigh and further upwards, usually there are no perceptible symptoms and most of the time it is painless. So one does not know about the movement. If you have any of the above symptoms in calves, it is necessary to visit ER. If the symptoms are confined in the thigh; it is likely to be due to cramp. If the pain subsided, after some time, that too is a pointer to the cramp. Again, any sudden severe persistent pain would warrant an examination by the doctor to ascertain the cause, though, just a thigh pain would be more likely due to peripheral arterial disease (PAD; decreased blood flow in the arteries), pinched nerves in the back etc.
Please feel free for your follow up questions.
A cramp can cause lingering soreness for some duration. Severity of your symptoms would dictate further course of action like medical assistance immediately or during the routine hours.
It is privilege assisting you.