Hives from Sulfa Antibiotics - 2 weeks since last pill, still get hives mostly in the evening. Is this normal?

I have been taking bactrim for decades without issue - this last time I got full body hives, weakness, and fatigue. I was prescribed steroids and taking antihistamine religiously. Its been 2 weeks since I had my last antibiotic and I still get hives mostly in the evening (4pm+) and they are gone by the morning. Is this normal?