What is a white itchy rash on my feet?

See podiatry: White itchy rash on the feet is too broad of a symptom, to begin answering your question. A photo would be quite helpful. A biopsy would be definitive. Nonetheless, it should be checked.

See a Derm: Another possibility is to see a dermatologist. Visual inspection may be helpful to make a clinical diagnosis and review possible treatment options.

See your M.D: It is hard to tell without seeing the rash. It could a fungal infection. Your primary may be able to treat or refer you to appropriate specialty.

Athlete's foot?: The commonest diagnosis is that of athletes foot. See your pcp and if he or she gives you the same diagnosis then you can treat with an antifungal like lotrimin (clotrimazole).