M.C.
I had a reaction to Naproxyn. Pulse racing, chest burning/itching. I can take Tylenol and Motrin (1 pill) without issue. If I take 2 pills - the regular dose, I don't feel right.
When my son was 11m old we gave him Amoxicilin for an infection. Woke up SCREAMING in the middle of the night. Went to change his diaper and he had full body hives. I had never seen hives before. Had to call the dr. to ask what to do. The Benedryl worked quickly, but he had little purple welts all over his body (including his face) for about a week. People would stare. I wanted to cry.
Another thought. The fact that she was in a pool may have had something to do with it. Is it possible that one of the pool chemicals helped cause the reaction? I would keep her away from Naproxyn, but would lean towards some type of combined reaction if she's been able to have tylenol and motrin prior to this without a problem.