33 weeks pregnant with 1st baby

I have lots of pelvic and lower back pain my vagina has lots of throbbing and pressure when I pee it feels like I can push him out I have the constant need to pee I’m constipated and one minute I’m cold another minute I’m soaking with sweat from being hot I’ve had this for a week now even went to the hospital when this first started and they sent me home saying i was still closed my baby is also big what could this be preterm labour ? I’m not sure any suggestions or advice?