I have been nauseous for a little over a month and I am not pregnant any ideas on what's causing it?

Gastrointestinal . May be a GI issue -gallstones, liver, stomach conditions can cause. Constipation can cause. Kidney problems, sometimes hormonal fluctuations associated with menstrual cycling can cause (higher estrogen levels). Birth control pills, many other medications. Unfortunately - there are many many causes of nausea.