You are 33 wks pregnantif I am not wrong? The back pain
at this stage of pregnancy
can be due to-
due to ovrstress to back muscles in adesting with gravity.
A vulvo vaginitis
Bladder problem&urinary problem ---& many more.
You have to consult a gynac for proper dignosis & T/t.
For time being you can take tab. Duadilan 1 tab. twice a day to control your abdominl pain ,if it's too much.