Post-surgery rash and menstrual changes?

Prior to surgery, I was on a 10 day pre-op liquid diet during which I lost 12 lbs.

Day of surgery, I was given prophylactic antibiotics via IV and the nurse told me I had developed a rash on my chest afterwards, so now this is an allergy to me apparently

Two days later I woke up in the night literally yelling out in pain because my arms, shoulders, and hands were aching and hurting worse than anything I'd ever felt. I got up and discovered I had big hives all over my chest, face, and arms. Called the surgeon, he said this "wasn't normal" and deferred me to the ER. They determined I was having some sort of allergic reaction to the new medicine and so, 2 days post-op, I stopped all nausea meds, all the anti-spasmodic for my tummy, and all pain meds. They gave me a big dose of prednisone and I was better.

Fast forward to now... one month and 3 days post-sleeve. I still have this ridiculously itchy, hivey rash on my neck and chesy. I stopped using perfumes, stopped wearing necklaces, no changes to my detergent/soap/lotion. My doctor just seems absolutely perplexed, which is annoying to me. It has not spread at all... just my neck and chest.

Taken it upon myself to do some heavy Google research and found that there are several people claiming they get itchy rashes with ketosis. I am in full-blown ketosis right now and have been since day 2 of the post-op diet. Anybody like to weigh in and give a testimonial or similar story or info or insight or... ?? Anything to make me feel like I'm not nuts lol.

Also - I was on my period when I had surgery and, as many others have said happened to them, I then ended up having a longer period with spotting for about 4 days. Now I am supposed to start my period again and I literally had the tiniest bit of blood after sex and now nothing?? Full cramps, craving, bloating, and everything else but no bleeding. Not pregnant... tubes tied. Just wondering if anyone had anything similar??