you should not stop all medications like that as it will cause more problems than benefit.
Specially when you stop meds like novolog, lisinopril, byetta.... means you can have serious health effects from uncontroled diabets and blood pressure.
Anyway, it is not possible over the net to physically evaluate the rash as that will help to know the diagnosis.
Drug reactions are usually all over the body and not in one particulaar area. But that is not the rule.
You should take your meds as advised by your physician, and have physical exam of the rash by local physician in order to make the right diagnosis and treat it accordingly.
Meanwhile you can take benadryl ( causes sleepiness) for the itching problem.