Sex then cramps and vomiting?

So my husband and daughter and I went out yesterday and I ended up walking over 4 miles. When we got home that night my husband and I had sex and then within 20 mins I was cramping like I had to use the bathroom. I went to the bathroom and immediately felt like I needed to vomit. I ended up vomiting and cramping to the point of tears for about 2 hours then everything finally stopped. Tonight I’m starting to cramp again. Is this the start of labor? I’m currently 37 weeks 5 days. As of last Tuesday still no dilation and cervix is very soft.