I had unprotected sex a week ago now & i experienced frequent urination for 2 days then it stopped i took a pregnancy test and it was negative.. any idea what causes sudden frequent urination?

It could be from urethral or bladder irritation. Try drinking water and sit in a warm tub twice a day. If it persists you will need an exam and urine test

Your symptoms were likely from mild trauma to the urethra. If your symptoms have subsided, you need not be concerned. Get HPV, Flu and Covid vaccines. Wish you good health! Safe sex: https://www.hopkinsmedicine.org/health/wellness-and-prevention/safer-sex-guidelines