There is a tiny knot on top of my hand that seems to be in my vein. i especially see and feel it when i ball up my fist. could it be a blood clot?

Unlikely: Although small clots can and occur from trauma. More likely you are encountering a valve in the vein in your hand.

Yes: Phlebitis in that area is a possibility. Probable due to trauma as long as there is no redness or extension there is no reason for concern. Take Motrin and put a heating pad when idle and should resolve in a few days.

Nonsense: Valves in veins are very delicate and flimsy structures, i would like to hear from a reputable phlebologist or vascular surgeon that he can feel a valve in a a vein.