What Causes Itchy, Red Rash On Neck And Nausea?

I have an itchy red rash on my neck. I wake up every morning with irritated lungs; sometimes with nausea. Am fine as soon as I get up. I sleep on a medslant. I eat sensibly and organically, excercise at least 20 minutes per day; usually more, drink plenty of water, and get 8 hours sleep. I am 5'5" and weigh 145, but have difficulty losing weight. My normal body temp is 97.2, but lately it is more consistently 96.- every day. Should I be worried about my thyroid?