I get that sometimes and it always happens right before I start to leak colostrum lol that's how I know to stuff tissue in there so it doesn't get everywhere haha, always call your dr about any concern though.
I'm 16 weeks and I have a lot of Sharp pains in my breath. And, the come so randomly. By boobs have been tender since I've been pregnant. I like to take bubble baths or warm showers to relax my breast muscles try it.
Maybe you should call but i had that happen kinda right before my colostrum came in, and my nipples felt like someone was stabbing then with needles :( i would call your doc though, and you can get your colostrum pretty early too mine was at about 28 weeks but my friends was at 12 you can get it at any time :)