"Getting more than the recommended amount of zinc can cause adverse reactions, often involving the stomach and intestines. The first sign could be a metallic taste in your mouth after taking zinc. Additional symptoms of too much zinc include decreased appetite, cramping pain in the stomach, nausea, vomiting and diarrhea. People may also get a headache, dizziness or drowsiness after ingesting zinc. Taking zinc supplements with meals might help ease some stomach distress, notes the University of Maryland Medical Center, as well as help determine if stomach distress is a side effect or a symptom of too much zinc."
Theres quite a bit of instances of people complaining of headaches after Zinc so I would drop that first and see if it subsides.