Redness on the skin of the neck and chest skin could be due to an allergic reaction. Medicines are one of common reason for such an allergic reaction. The medicines you are taking include a non-opiate painkiller (Naprelan), an opiate painkiller (Lortab), an antidepressant (Wellbutrin) and an anti-allergy drug (Zyrtec). Ironically, any medicine can cause an allergy.... even an anti-allergy drug! In addition to medicines, many other factors can cause allergy like: local contact with an allergen, sunlight exposure, low or high temperature, stress etc. You can consult a dermatologist to confirm or exclude allergy. If an allergy is confirmed, several laboratory test can be performed to identify the allergen.