Hi, and thanks for your medical question on eHealth forum!
Yeast infection or thrush is at times very difficult to treat. You may need to take oral antifungal pills twice a week for 3-4 weeks along with local application of antifungal cream. There are many types of antifungals available. Take an OTC antifungal with a combination of two or more anti fungals. Use both oral and local application. At times both partners need to be treated. Provided it is indeed fungus, then only try this. Antifungal tablets are strong medicines and should not be taken otherwise. So start with cream and if it helps, start the tablet.
Various reasons for recurrent fungal infection are incomplete treatment, treatment resistance, co-existing dermatitis, diabetes and low immunity. The risk of vaginal infections especially thrush or fungal infection is higher in women on contraceptive pills containing estrogen. Changing the pill type often helps in these cases. Also, use a condom to prevent infections. Discuss this with your gynecologist. Take care!