I Gave Blood About 2 Weeks Ago. One Arm They

I gave blood about 2 weeks ago. One arm they couldn't find vein after poking around. Then did other arm. Both arms totally scabbard up in a day. Now a rash is all the uo my arms and scabing at arm pit side. Rash is going to my chest. Urgent care just gave me an ointment and steroids. Should I go to the hospital? But ask for what test