Is it psoriasis?

I've seen a doctor who refuses to listen when I said I think it's psoriasis she just said its a rash use some moisturising cream. I don't even want to visit again as every time I book an appointment it's her. I know it's not just a rash I'm in pain it's now started on my eye lids my back is covered. It all started after having my second child by c section I have even had to give up breast feeding because it was on my nipple Please someone tell me a way to treat it I want to scratch all the time some times I don't even notice I'm doing it and my 5 year old tells me off. Every picture I see of psoriasis is exactly what's on my back even my brothers girl friend who's mum suffered from it says it's psoriasis