What are the signs of PRETERM LABOR??

I went to the doctor a few days ago and thought I had a yeast infection due to increased discharge, so my OB checked for that. Turns out I didn’t have a yeast infection and everything is normal. BUT, ever since my appointment, I’ve been cramping like intense menstrual cramps and I also have lower dull back pain. Today I woke up at 1:30am in the morning and it’s still going on and can’t sleep, but now I have chills and pooped twice within 10 mins which is not normal for me. Not to mention I threw up only once this morning when I woke up and I NEVER throw up. I’m 34 weeks pregnant and I have also delivered my first born at 34 and a half weeks. My water broke with him though. Is this normal or a sign of preterm labor? Or could this be because my OB checked me for a yeast infection with a Q-tip?