Yeast infection...

I just saw the doctor last week and during my annual was told I had a yeast infection. I took the 2 doses of  medicine and the infection cleared up. This week I am visiting my fiancé and we were sexually active. After the first time, the discharge was normal, but 4 days later the discharge is back. It's not that bad, but white- cottage cheese/typical yeast inception signs. 
My question is can I possibly be having a reaction to my fiancé's seamen or does he have a yeast infection too? What could be going on?
(We are exclusive and have no STDs)