Hello. My Fiance Seems To Be Having A Terrible Reaction

Hello. My fiance seems to be having a terrible reaction to Aleve. He took it about an hour or so ago and now has a severe rash, welts & itching. He is breathing fine at this time but is very red. I gave him 2 Benadryl to help but he seems to still be itching. This happened in November with a bad scare. We didnt think it had anything to do with the Aleve as the Doctors suggested it was Polycythemia Vera due to high testosterone but now- I'm wondering if this was the cause of his breathing & itching problems.