Whta are the symptoms of deep vein thrombosis?

Variable. Sometimes there are no symptoms. Typical symptoms include leg swelling or pain in the legs, especially the calves.
Pain & swelling. Symptoms can be none. The most common symptom is pain / ache in upper calf and or behind knee. Swelling, tenderness and redness in the leg can occur.
DVT symptoms. Dr. Simpson is right, sometimes dvts have no symptoms whatsoever (unfortunately frequently). The classic symptoms of DVT are pain and swelling in the calf. Sometimes they are also associated with redness and warmth. Again, though, there may be no symptoms at all.