I Was Given Diltiazem In The Hospital Through IV, And

I was given Diltiazem in the hospital through IV, and was given a prescription Diltiazem CD 120 mg. Ive been on pill for for two weeks. For a week I been sweating profusely with it, then for the past four days my chin started itching, and I noticed I have a rash on my chin, and the last two days it has spread on my face and body. It burns and itches, and I have two or three spots of hives on arm and chest. I was told to stop taking it. So I did. Since I stopped taking it, it hasn't spread, but still itching and burning and rash is about the same. If it is the Diltiazem, how long should it take for the reaction to go away, being I had both forms of it (IV and oral)?