Suggest Treatment For Urticaria

Hi, My father is suffering from urticaria on most parts of the body since a long time (8 months). We have already tried various treatments like antihistamines like Allegra, Montek LC, Altiva, Avil along with Prednisolon usually twice a day. We have also taken ayurvedic and homeopathic treatment. Allergy test has been done and we are avoiding the food items and medicines suggested. the test did not reveal any other special reason for urticaria (antibodies etc.). Please suggest a suitable medicine. You can also give us your contact details if you are in Mumbai. thanks! Manish Sharma