Red Pimple Rash Thats Spreading, Suggest Me The Remedies

I have a red pimply rash behind ears, running down my neck, chest , stomach, back, inside belly button and now I have small pimple red dots on top of legs and arms. I do have a areas which are very red and much bigger. No blisters, Not itchy all the time as been taking antihistamine, but occasional irritation especially when i got warm. Ive not been feeling great for some weeks. Temperature is normal now but previosuly been about 38. It dosent seem to be getting better. I have hypothyroidism and pernicious anaemia and both are stable. Please help me come up with some answers.