I have a rash that comes and goes, they look like scratches and mosquito bites. they don't hurt but are itchy. they disappear and then ease away.

Urticaria: This rash you describe sounds like something called urticaria (hives). Urticaria is caused by histamine release. It can be due to a number of conditions including allergic reactions. Sometimes we don't find a cause for this and it is called idiopathic urticaria, Check with you primary doc and discuss the symptoms further. It is can be treated with antihistamines.