Have you tried the antihistamine yet to at least calm down the itching? If there is something there, your body makes histamine, which goes to the location to prevent it spreading, and it causes the itching sensation because it irritates the nerves when it causes the area to swell a bit.

I read you tried something shampoo and you felt it itch all the way down your front...this is not "bugs", this is the body's natural reaction when the histamine floods the area and goes down the nerve pathway. If you are always itching and scratching your body will continue to make more histamine and it will be a vicious cycle. At least try it, and get rid of the symptom to give yourself some relief. <chemist friend>.

When you say "bite", please describe...how big, like a pin head or bigger like a mosquito bite, it is raised bump, open or closed, dry or weeping and if weeping what color - clear, white, yellow, blood? Is it one, many, does it go through a predictable time period or random. Describe like I am blind.