Head & Shoulders works because the topical zinc helps kill the fungus that can cause pityrosporum folliculitis. I don't think zinc supplement pills have the same effect. I think the only pills that would work would be an antifungal pill like ketoconazole.
My guess would be seborrheic dermatitis rather than perioral dermatitis. I would use a dandruff shampoo such as Nizoral every day in addition to hydrocortisone twice daily until it gets better. Once it's better then keep using the Nizoral about twice a week to keep it from coming back.
I totally agree with with all other posters. Your own will-power is going to be the most important thing.
Something I've read about recently, to help control compulsions that you can't seem to otherwise control, is taking the amino acid derivative called n-acetyl-cysteine (NAC) about 1000mg twice daily. It's mainly described for compulsive hair-pulling, but I think it may be worth a try.