Hello, I can understand your concern for body itching with welts. It is quite common to find such kind of thing in our usual practice and is medically known as Urticaria. Urticaria is a common condition caused by bursting of allergy producing cells. These cells which are known as mast cells are bursted and the chemical inside them is released it produces a rash . There can be multiple factors producing this condition which are included in day to day life and some times it is actually not easy to find one exact cause. In my patients I prefer to give oral anti histamine like Des-loratadine or levocetrizine under medical advice. I reassure you fully that this is not related to Lyme disease so don not worry about the same. You can take further guidance form a dermatologists. All the best.