Thanks for your query,based on the facts that you have posted it appears that you are pregnant (21 week) and have urgency incontinence
This is most likely to be due to pressure of gravid uterus
over bladder.Get your routine urine test done to rule out any infection .If there is no evidence of UTI you need not worry at all as this problem will get resolved of its own after few more weeks when the uterus will get raised in abdomen and pressure over bladder will get minimised.
You may continue taking Citralka and a Ampicillin
for few more dyas.