30 weeks pregnant with back pain,vommitting,pelvic pain, and diahhrea is this normal? ?

This is my first pregnancy and im having lots of back pain and pelvic pain my doctor told me the pelvic pain was just with how low the baby is I have been having diahhrea and vommitting as well has anyone else experienced these symptoms? I have also been having braxton hicks for the past month my doctor doesn't seem to think it means im going to have a premature labor