For reasons beyond my understanding our body builds antigens to this drug we may have taken for years - an allergic reaction begins. It can be
in the
form of a rash, hives or other SX (symptoms). If not recognized the allergic reaction can become severe.
I don't know if that is what is happening to you. It's many of allergies initially presented. Don't mess around my friend in pain - contact your prescribing physician. Let him/her determine where to from here.