it sounds like thrush to me.
I was told by my pharmacist that if you get a powderd form of a pro-biotic, you can apply it directly to the affected area so that it goes straight to work and sorts out the imbalance that might be there.
give it a try - if it does not work then you will need an antibotic.
Its quite normal when a comparative very big and thick penis goes inside vagina then there may be some itching. But all this will heal automatically. No need to worry.