About 3 Wks. Ago, I Was Put On Macrobid For

About 3 wks. ago, I was put on Macrobid for a bladder infection. After taking the full amount, I got the bladder infection back and the dr. prescribed a refill. The day after I took the last pills, I started breaking out with red, itchy, burning blotches all over my body. I have tried ice packs and TriCalm. Today, I was told to take a cortisone cream, 3 times a day. The itchy, burning feeling is driving me crazy. I was told this will eventually go away. Will it and how long can I expect to have it? I feel that along with the itching that my body feels like it's burning from the inside out. I need help. I can not take benedryl because of a bad reaction years ago.