4th day of antibiotics following on from confirmaction of uti 3 days remaining. symptoms not improved. could it still clear?

Possibly: You should be starting to feel better. So long as you aren't running a fever, have flank pain or feel downright miserable, you can stay the course while pushing fluids. If symptoms persist when antibiotics are gone, see your doctor again.

Which symptoms?: You should be feeling appreciably better within 4 days of therapy if the organism causing your infection is sensitive to the antibiotic chosen. Go back to your doctor.