Can antibiotics from having a urinary tract infections cause my period to be late. negative test also i have cramps in my side with headaches?

Unlikely: Antibiotics don't usually affect your period. However, if you missed your period and are cramping, you need to see your doctor. These are symptoms of an ectopic pregnancy. Its not that likely but its serious enough to warrant a trip to your doctor for a blood test. You may also want to make sure the UTI was treated by the antibiotic. Some organisms resist standard antibiotics. Best wishes!