I have a raised red rash which started off on my thighs and has spread up my back and stomach and down legs and arms itchy, some yellow scabbing?

Impetigo? Get seen!: It sounds like you could have a rash that became infected. You may need oral and topical antibiotics as well as a surgical scrub like hibiclens or some hydrogen peroxide to clean the area. Dry itchy skin becomes cracked, rashy and infected skin. I think you should head to a physician for evaluation especially because of the yellow crusting. Benadryl (diphenhydramine) may help with itch.