I think that lichens planus has alot to do with the acidity of the body. I have found that if I keep my (urine) pH up (~6.2 or higher), that the itch goes away and the bumps stop appearing. If the pH goes lower, the itch starts and the bumps start reappearing.
I started noticing this because I would get something like water blisters in my mouth around meal time. If figured that my pH would be lower around meals. I also noticed that the blisters would pop easily if my pH was up, and would be harder to pop if the pH was low.
I think that lichens planus might be a reaction to acidic sweat.
I have used baking soda to raise my pH