It very dry itch if I strach it to hard it to hard it cut open

Crotch rot?
Mainly happens with campers where personal hygiene isn't the highest or lots of walking/biking etc.

First buy some 1% cortisone cream and spray, or just the spray, even though it's more expensive. Keep clean, rinse well, no scented soap, pat dry no rubbing, air yourself out for a good half hour each day by walking around naked or lying on your bed.

If that doesn't work you need to see a doctor.