Bites or heat rash prickly heat

Sounds like rosacea. Heat aggravates blood vessels, which aggravate the skin, and deliver bumpy red spots (with or without flakes), usually around the cheeks, nose and eyes. Strongest treatment for rosacea is usually antibiotics, such as lymecycline. Can take 1-6 months. Be mindful, however, that antibiotics wreck the gut biome (good bacteria), and may make psoriasis worse in the long term. It's a risk-benefit thing.

Rosacea can also appear on the body, chest, and back. Not just the face or neck. Hives normally itch, burn or sting. There is no mention of those in your posts. Don't discount rosacea (or something close to it).