Can a uti or bladder infection cause lower back and abdominal pain that is pretty bad ?

UTI pain: Yes, but some sexually transmitted diseases can cause the same symptoms or worse, and also infect the bladder. Go to a clinic and get a urine/vaginal culture. Infection can reduce your fertility if not treated.

Maybe not UTI: A urinary tract infection could do this, but several other potentially serious problems also are possible and perhaps more likely, depending on details (lower vs upper abdomen, vaginal discharge, fever, diarrhea, other symptoms. STDs may be possible if you are sexually active, and can cause urine abnormalities similar to UTI. So don't mess around with this -- see your doctor ASAP.