u/Far_Fig_1572

Any insight on what could be causing this rash? First pic is yesterday and second pic is today. I thought it was because of an allergic reaction to a piece of shrimp I gave her. She threw up when I was asleep and had diarrhea yesterday. I gave her some rice, lots of water and monitored her and she was getting better. Then overnight it became worse this morning. She is licking her behind a lot, so I’m wondering if that has anything to do with it? Help.