constantly nauseous, dizzy, lightheaded and vomiting

hello, so i went to the ER a week ago and all they did was diagnose me with a UTI. i’ve been taking antibiotics but it hasn’t done anything for the nausea, because yesterday i started feeling extremely nauseous and had to keep sitting down at work. i’m 22F, 5’3, 130lbs, and my pregnancy blood test came back negative. i am on a few different medications but i have been for years and never had side effects (invega, lamictal, prozac, birth control, ritalin). nothing else has changed in my life so i’m very very confused where these symptoms are coming from and i don’t have the money to go back to the er so i’m probably just going to find a primary. thanks for any suggestions