This morning, i ended up vomiting for no particular reason. i had eaten breakfast, but took 2 5htp tabs instead of 1. could that be the problem?

Very possibly: 5-Hydroxytryptophan (5-HTP,oxitriptan, INN), is an amino acid involved in biosynthesis of serotonin & melatonin from tryptophan. It serves as an antidepressant, appetite suppressant, & sleep aid. Acute moderate gastrointestinal effects (vomiting, diarrhea) are common upon taking 5-HTP, probably due to rapid formation of serotonin in the upper intestinal tract. See doc esp. if persistent symptoms.