Abdominal/pelvic ultrasound/ct negative exept small cyst on left ovary pain on my right side of my stomach nausea constipation/diarhea headache hurt every time I eat what's next?

I agree with GI, but. A treatable GI problem is not out of the question. The headache though...Are you sleeping well? Do you clinch teeth when sleeping? Do you have panic attacks? If GI workup unremarkable, and they often are, then must consider"top down" approach. Anxiety and bowel function can be linked and called irritable bowel. Look up this and sleep bruxism. It's easy to treat if GI finds nothing i see it alo.
GI evaluation. Looks like you need to be referred for an evaluation by a gastroenterologist. Symptoms appear similar to a gastric ulcer and possible irritable bowel syndrome.