Had iv contrast 3days ago for mri and arm has dull ache from shoulder to wrist, normal? did bleed out a little after tech took needle out. tiny bruise

Arm ache: This does not sound like a reaction to the MRI or contrast and i doubt that you developed a phlebitis from the IV puncture or insertion. Perhaps you were lying in an awkward postion for a lengthy time and sustained some sort of strain or sprain. If you can tolerate nsaids like ibuprofen, this would help. See your md if symptoms persist or worsen.