I've had severe vaginal itching buring for 3 months cultures and blood tests came back negative . any ideas? my ua did show moderate epithilial casts.

Need more info: I'd need more information from you - as to where is the itching (inside, outside), any associated symptoms - discharge, bleeding, skin lesions. History - any change in personal hygiene products, detergents, sexually active or not? What tests were done and what are the results? Were you tested for diabetes by chance? Did you have complete blood count?

Need to examine: It is not feasible to provide a meaningful opinion without examining you. You may wish to consult a dermatologist if your current doctor has not been effective. Have a healthy diet, exercise, drink plenty of water, have safe sex, and get HPV vaccine. Wish you good health! Nutrition: http://www.choosemyplate.gov/.