Mybf fingered me&itwasburning,since then having abdominalpain,backpain,feel the need to poop,he ejaculated just near vagina,pregnant?acidity,infection

Possible infection: Pregnancy seems unlikely from that particular event but an infection is certainly possible. If your symptoms don''t go away in a day or are severe, you should see a doctor

Possibly: A woman of child bearing age who is sexual active with new pelvic complaints should be seen and evalauted by a doctor. While pregnancy is possible, and can cause this constilation of symtpoms there are other possibilities that need to be evaluated.

Infection : First you could be pregnant, please take a test and take precautions, eat healthy, don't drink, stop all meds/drugs. The symptoms could be a urinary tract infection. You need to be evaluated as soon as possible. The back pain could be a kidney infection. This could be a very serious, it could also be a pelvic infection which also needs immediate attention. Either way you need a urine evaluation.