I Started Apriso 5 Days Ago. I Have Had No

I started Apriso 5 days ago. I have had no side effects so far. This afternoon, my face was very flushed and warm to the touch (no fever). I have had an allergic reaction to Bactrim in the past. The Apriso lists possible side effects from other sulfa based meds. Could this be the start of a reaction or purely coincidence?