I itch very bad down there - It isn't inside my vagina, but on ALL of my skin down there - inside and outside both lips, even reaching back to my anus. It hurts very bad when I pee. It itched a little but then me and my husband had sex and then we showered and used the shower head(I always use the shower head down there to help me clean myself better after sex or on my period and have never had a problem). Now my itch is more intense and it hurts worse to pee - enough to where I will hold it for a few hours just so that I only have to pee once or twice a day. My husband had a slight rash but he was getting over it when we had sex - did I get it from him and what can I do for it?
Every once in a while, I will feel a jolt of pain down there. It isn't swollen, but it is slightly red. Please help - sometimes the pain and itching is so intense that I can't even sit down.

P.S.
My water has a lot of calcium and minerals because the pipes are very old and hadn't been used for a while before we moved into our condo and after I had my baby, I couldn't shower at my house because it caused the same thing.