ok, this is gonna sound crazy, but I'm gonna go out on a limb and say this is an actual physical condition that you have. it's not serious like life threatening or anything, but it's like headaches or frequent colds.
People may be tempted to attribute this kind of thing to a psychological cause, but especially because it's accompanied by itching, I'm gonna say it's physical.
If you eat a lot of sugar, candy, junk food, salt, or processed food, including lots of spices, then you need to cut back on those things and focus on eating more whole foods like whole grains, vegetables, and fruits. Experiment with meat and dairy. See if you get worse or better if you cut them out or increase them.
You might continue to be slightly grossed out by random things, but the feeling will lessen and so will the itching. I would also suggest trying a Chinese herbalist or acupuncturist if there's a good one in your area. Good luck.