Go to the doctors or hospital asap. It's an infection and you need to get treated with antibiotics. Infections are not good for the baby. When the rash is cleared up, start wearing deodorant between your legs. I've had.the same problem and the deodorant prevents the rash from coming back
Sounds like a yeast infection or a bacterial infection.
You definitely need to be seen if the rash is having discharge, if its youre own discharge and its any color other than white it needs to be checked out. After all this clears up the deodorant on your upper thighs is a great idea, also baby powder down there. It will help keep things dry. Im a cna and I had a patient with a constant rash down there, we used a medicated powder from the doctor and after a few days switched to baby powder and it went away and never came back. Stay dry, wear pads and change them often to keep away any wetness. But get all of this checked out first then try hone remedies after. Infections left untreated can harm the baby and make you sick as well.