I am 19 weeks pregnant and have a bladder infection (went to the dr on wed). I am still having severe pain in my lower abdomen. What should I do?

Ob/gyn. Go see your ob/gyn asap. They can analyise the urine to look for any lingering infection and also check you for any other cause of the pain. They can also check to make sure baby is ok and growing normally.
See physician. You need to notify your physician. The pain can be from the infection, if the antibiotics you took did not clear infection, or the pregnancy. You should be re-evaluated either way.