It could be a UTI, they're pretty common during pregnancy and I've heard that they sometimes present with less symptoms than you may have experienced in the past. I had this a few weeks ago and went in for a test just to check. My urine looked "perfect" according to the nurse, and she said sometimes you may feel this just because your uterus is right on top of your bladder. How far along are you?
I get a terrible ache down low every afternoon. I usually notice it when I stand up after I've been sitting for a little while. It feels better if I kind of lift up on my belly. Mine is just pressure from the ever-growing butterbean. I had a support belt last time that helped a little bit.
Re: Weird Pressure