could be a yeast infection, or just the heat, try some baby powder, if that did not work then you may need to see a dr. to see if it is a yeast infection.
I'm not a DOCTOR but,
It depends on where the itching is, if you have the itching outside propably not, inside you better go anyway to be absolutely sure, to the dr and have him/her check you out, you don't want to mess with something like that. When it comes to your body.
If it is a STD it could leave you sterile and you can infect someone else and so on so on. Do it right away.