Hi, I have got tinea versicolor 3 month ago took 2x200mg ketoconazole for 7 days and now it's back and now on my face what should I do?

Infection. It is a fungal infection w/ the spore & pseudohyphae that sometimes not easy to eradicate completely. Keep a good personal hygiene. Also, your immune system and treatment received are important. Make sure you keep your fingernail short and always to wash your hand. Go to see dermatologist. Perhaps in addition to oral antifungal , you also need antifungal cream. Discuss further with your derm.
Get checked. If it returned so quickly i would see a dermatologist to make sure you had the proper diagnosis.