Hi, I can understand your concern for itching around waist, armpits and wrists with bumps on legs. It is appears to be from query that you are suffering form Urticaria or hives. It is a common condition caused by bursting of allergy producing cells known as mast cells due to certain aggravating factors present in the environment. As the chemical inside them is released it produces a rash which you have mentioned. There can be multiple factors producing this condition which are included in day to day life and some times it is really difficult to find one exact cause. The long term effective treatment for this is by oral anti histamine like loratadine under medical advise. It is one of the drug which is not having any side effects and can be taken for long term usage. Take care.