I have a cold, my fever went away, now it's back. Any ideas?

I’ve been sick since Monday the 21st. I had a fever that got up to 103.2, with body aches, stuffy nose, sore throat, and all over horrible achy feeling. I finally broke my fever yesterday, but today i decided to do the dishes, now my fever is back but it’s staying around 100 with ibuprofen in my system. My nose is still a little stuffed up and i have a hoarse, dry cough. Any ideas why my fever came back? I possibly worked my body too hard doing the dishes?