What causes a recurring neck rash with severe nausea I'm a 45 year old female

Uncertain. This can't be diagnosed with the information that is available. A history, physical examination & other studies may be needed to determine cause/causes. Once accurately assessed a treatment plan can be developed.
Those . Those are not usual symptoms. Keep a food log and see if there is a relation to the food that you are eating. Then take the food log to your doctor and discuss your symptoms. If you have vomiting, shortness of breath, fever or new complaints then you need to be seen as an emergency.