Just curious...did you have covid? Cannot tolerate temperatures over 80 degrees and get welt type rashes that burn and itch very similar to yours. I gave had fibro for 30 years and never had rashes until covid. They eventually just go away for me . I do have a few scars. Weird stuff! My doctor gave me hydrocortisone cream and antifungal. Hope you get some answers!

It only lasted about an hour. It's not the first time I have red marks on my neck. They come and go

I've never seen those before. How long have you had this? Maybe a type of hives?

Thats not a rash it looks like trauma from scratches or something else

Haven't seen a rash like that before