Itching with associated rash may be due to infestations with parasites (such as scabies, mites, or lice),
insect bites, hives, dermatitis ( atopic dermatitis/ allergic dermatitis/ contact dermatitis) and even dry skin. On the other hand, systemic diseases that can cause itching include liver disease, thyroid disease, diabetes, and cancer. Some types of medications may also cause itching. I recommend that you have this evaluated further by your doctor for proper management.