If u havent dewormed in awhile, you might want to submit a fecal sample to check for parasites and do a fecal egg count to determine how much load (if any) he's carrying. You may be able to drop off sample at your vet's office and save the farm call fee. These tests will determine what dewormer--if any--is necessary.
Also, iodine is fairly caustic so may aggrevate the wound & cause more itching. Fly spray around the wound (via cloth) or a product like "SWAT" will keep flies at bay. Try to keep the fly repellents out of the wound, though.
