I'd be going to the doctor also, you never can tell what your skin is going to do in pregnancy, it could easily be some sort of allergic reaction that you suddenly developed for no reason at all other than hormones changing your body chemistry.
If it is some sort of boil, there's a type that does infect the whole body through the lymph gland and is recurrent, so you might need antibiotics to get on top of it. That's possibly a worst-case scenario, but it is worth getting it checked out for your peace of mind.

During my first pregnancy, my sweat turned acid for some reason and would leave me with big stripes of blisters wherever my clothing rubbed. I had to use cortisone cream to stop me scratching holes in my skin! It only happened in the one pregnancy, but it was absolutely horrible for a few months.

Preggers skin knows no logic! I hope all goes well for you,

Kerrie