Early Labor Signs

How did y'all know labor was starting? I'm 39 weeks and got myself a yoga ball yesterday just to help prep for labor and to have to take to the hospital. I bounced on it for a couple hours just while we were watching tv and had crazy pelvic pressure afterwards. Got up in the middle of the night and got super sick (which is abnormal for me as I've actually felt great this pregnancy!). I was sweating, had diarrhea and felt like I was going to vomit... felt better after I got sick though so I thought maybe it was something I ate? But I'm up for the day and still have crazy pressure and cramping in my lower abdomen and back. FTM so just wondering if this is how the end is or if it could be labor starting? Any advice? (I've also been timing contractions this morning... definitely feel different than BH, just trying to watch consistency now). Haven't lost my mucus plug or anything yet...