Over the last few days I've had sore veins in a few different places. Behind my left knee, then side of right thigh and now my left buttock has a sore spot. I'm really scared of blood clots because a friend died of one. I have no swelling or redness, it just feels like bruised veins almost. The pain in my buttock is a bit stabby but more tender to the touch. If I had a blood clot I'd have swelling and redness and lot of pain wouldn't I? I don't know why my veins keep feeling tender but it's very weird.