Rash help!

Hi! I have been suffering from skin issues for 4 months now. I have seen dermatologists, an Allergist and done the patch testing. They all think it's autoimmune. I did see a Rheumatologist and had 23 tests run and the only positive was ANA which was 1:320 Homo but it had been at 1:160 for 8 years. My latest symptom is a burning rash that looks just like sunburn over my neck, chest, outer ears and stomach. It gets so bad I'm starting to feel it burning inside my body and getting reflux and loss of appetite. Does this sound like an AI rash? I do feel like my body is attacking itself. It just keeps getting worse and responds worse to heat. I have been staying out of the sun and it doesn't really feel any better. I am hoping for a skin biopsy this week but it's been a challenge getting a doctor appointment while the rash is there as it comes and goes. Thank you for any feedback!