I had that too. Lasted 4 days then subsided. Mine was like a dull ache but occasionally got stabby and hurt quite a bit. I am thinking it is round ligament...hurts and is so annoying. I'll take pain over nausea and vomiting though!
It could also be SPD starting, which is what mine felt like last time this early and this time as well. It's fairly normal and common but can get really uncomfortable. If it does get more painful as you get bigger mention it to your doctor for some exercises and such you can do.
Re: dull ache in crotch?