Thanks foe coming to HCM. You can try applying ice-pack and see if it helps. I am assuming blood was drawn from vein near elbow. If doctor could draw blood conveniently, it is less likely that needle was in wrong place. Your problem might go away on its own. But if you have got swelling in the area which is lasting 4 days after blood test
, or pain persist for next 1-2 days, you should visit the doctor. Small bruise
like discoloration around blood collection site is normal.
Wish you good health.