What Causes Urgency/frequent Urination, High Leukocytes, Swelling On Urethra Opening?

32 yr female Caucasian. Urinary Sx started 4d ago. No pain but urgency/frequent urination. Leukocytes in test were high and due to Sx urine was sent off for laboratory testing. Was given anitbiotic, 2x d for 3d's. Other than the urgency making it frequent urination, my urethra opening seems to be swollen and sensitive to the touch. I also I'm finding a little/tiny bit of urine is in have coming out in between visits to the restroom. So I'm actually leaking to put it in easy terms. If there's no sign of infection, what could cause this? And can I use triple antibiotic cream on the urethra for external relief?