I have a prescription for clobetasol ointment usp, 0.05% for psoriasis. i have severe itching in the groin area and would like to know if it'll cause a yeast or uti?

If the rash is fungal, applying only a topical steroid to it will make it worse (by lowering local immune response) and make it harder to diagnose by a clinician. Probably best to see a clinician for an accurate visual diagnosis and appropriate treatment. You can try an over the counter antifungal cream like clotrimazole or ketoconazole (if not allergic) twice a day until you see someone.

No it will not.