I went for a massage for my sore muscles the next day and the massage therapist told me it wasn't a cold. Just like getting a deep massage releases toxins that have been stored in your muscle tissue, the heavy lifting breaks down muscle fibers and dumps stored toxins into the body. My body was producing histamine in response to the toxins. That's why you're supposed to drink a ton of water after a massage, to wash the toxins out. The massage therapist theorized that if I drank a bunch of water it would wash out my system and eliminate the allergy-like symptoms, which in fact seems to be the case.
So wadda you know, I'm allergic to power lifting.