If the antifungal cream helped, then it was probably a yeast infection. But she also has to treat her yeast infection at the same time so you don't reinfect each other every time you have sex. So both of you do it at the same time and refrain from sex until both of you seem to be clear of infection.
we didnt have sex for 3 weeks and it went away. but then came back after i stoped using the cream
Yeast infections can be very difficult to get rid of. Did she treat herself with antifungals while you didn't have sex for 3 weeks?
yes, she used a pill thing
It can be due to chafing skin or eczema skin. Take some antihistaminic like Benadryl or Claritin and apply some calamine lotion on the rash. Also wear cotton clothes and keep the skin sweat free. If the symptoms persist then please get it examined from a dermatologist.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.