I am 37 weeks pregnant, my lower back is in pain, also have slight pain on pelvis and feel some pressure, also getting sharp pain in vagina, help?

37 weeks pain: Call your doctor-now someone is always on call/ go to ER. Any bleeding? May be labor or UTI( which at this point in pregnancy is significant)or vagina infection or pre-eclampsia or abruption. You are at term, call your doctor /go to ER.

Pelvic ligaments: Back & mid-pelvic pain w. 37 week pregnancy from pelvic ligaments mechanically stressed & loosened by hormone Relaxin; pelvis prepares for birth canal expansion. Pre-sacral plexus overlies ventral sacroiliac joint (SIJ) sulcus. SIJ pain can refer to mid-pelvis. SIJ subluxation evokes symphysis pubis joint torsion & pain in anterior-inferior pelvis. Consult Obstetrician. Perhaps SIJ belt indicated.