My Dear Welcome to Healthcaremagic! I have noted your details and concerns. You probably are having one of the two conditions which I will explain to you and also suggest how best you can get relief. In case the rash is only on one side of the body and some of the lesions seem to be getting filled up with watery contents, then chances are that you are having Herpes Zoster. The best strategy that works for this condition is to Use antibiotics and Acyclovir, an antiviral, for local use and taking Acyclovir or another antiviral by mouth for at least 5 days along with medication to control symptoms like pain, itching, and fever. However, if the rash is on both the sides and spread out diffusely, then this could be due to allergy or intolerance of skin towards some locally applied agent like a Deodorant, oil, perfume, some medicines or anything to which your skin was exposed albeit momentarily. In such a case, it would be desirable to have anti allergic medication and frequent sponging of the area. Hopefully, you will get well soon and contact me again for further information. Best wishes from Healthcaremagic!