Help please. when i urinate i get a big pain in my stomach. does it have to do anything with pregnancy?

Not really: If you have pain during urination it is called dysuria and usually caused by irritation of the bladder and common during pregnancy due to the gravid uterus pushing it against your pelvic bone particularly during the fist and the last trimester . If the pain is big , i think you need to see your obgyn and get some help. Good luck with your pregnancy.