Hi,
One can get yeast infection even without any sexual contacts, but with sexual contact it can easily spread, so one should avoid sex while under treatment. Penis, Scrotum and Vagina are places easily infected due to presence of moisture and lack of sunligt.
I also feel one month of treatment should have produced some improvement. If not you should go back to your doctor and seek his advice. If left untreated, it can spread to other parts and also easily spread to your partner.
Solace