Perhaps, the best way to get over it is to play in the dirt, make mud pies. Try and wear your clothes for two hours at first. There are the the wet butt wipes for grown ups you know, just a wipe or two and you don't go around smelling like ass. lol If you're at home, take a quick shower, if you feel you need too.
I have the a simalar problem with dirt, for another reason. A parasite infection, I still struggle with the mental aspects of it. When I see my husband pet his dog and go to bed, without washing his hands, his chances of getting laid are zip.
There is mass amounts of information about diet and ADHD on the internet. Perhaps you should google it. Most of all realize what happened to you as a child was not your fault. No longer give it any power of your life.