Thank you for your consult at DoctorSpring.com.
You seem to be having urticaria. its also called hives. It is a condition where there are red raised lesions all over the body with lot of itching. These lesions are of various sizes and shapes and they come and go on their own. They need prompt treatment. Urticaria may be idiopathic or may have a variety of causative factors, there is an exhaustive list available but to tell you the truth its really difficult to pin point one thing.
The best thing to do is to start prompt treatment for immediate relief. Tablet fexofenadine 180 mg once in the morning and tablet levocetrizine 5 mg once daily at night for 3 months. its necessary to take medications for atleast 3 months to suppress the process. You can apply calamine lotion on the rash to soothe it Twice a day till there is a rash. Urticaria can be caused by foods, medications, pollen, house dust etc.avoiding fish, milk, nuts for 15 days would be a good idea and see if it further helps you.
Please feel free to ask me in case you have any queries.