I also had the sensations that you did - the scalp, some biting all over, itching. I don't think I will ever be able to say what it was but I can definitely say that it was truly horrible and frightening and it happened only after I took a certain combo of herbs. Mine stopped the very night I took the first dose of Tinidazole - which is a cousin of Flagyl and is prescribed for protozoan infections.
I don't know how much Mebendazole you took but you may have not taken enough of if you didn't kill the things and merely made them scatter you may need to take Albendazole but for a longer period of time.
I still would not take internal parasite killing herbs with pharmaceuticals but the body wash with the dog soap like Kasima suggested may be fine....at least I would do that after or in between a course of meds.