Gave blood over four weeks ago. when drawn, my arm was shaking almost uncontrollably. it bruised dark purple, now gone, but still hurts. go see dr?

Any post: Donation discomfort that lasts that long definitely needs to be evaluated.

Minor injury: The shaking of your hand probably caused the needle to pierce and traumatize the vein and tissue. This caused a hematoma (the discoloration). You also may have traumatized a small nerve or caused a mechanical phlebitis ( inflammation of a vein). This could account for the pain. Lastly there is rare neurologic condition called rsd that can can occur from minor injuries. This in unlikely.