OUCH!!! Pains :(

For the last couple of days I've been getting pains in my lower abdomen (same place as you'd get period pain). It usually lasts an hour or two. At the moment it's so sore I can't stand fully upright. It always seems to start when I need to pee but can't get to a loo straight away so have to hold it for a bit, and stays sore even after I've been to the toilet. It's not really cramping as such because it doesn't come and go, it just stays sore constantly for a while. Anyone else get this? I can still feel baby wriggling so not too worried, just wanted to know if this is the "stretching pains" the preggy books talk about!
I see my Ob on Thurs so can ask him then, just thought I'd ask you knowledgeable ladies first

does it feel like its bruised, as if you've benn kicked in fanny?  I get that and think its the pubic bone seperating. I imagine a fukk bkadder puts more pressure on it

Ooh I remember those at about your stage - can be really sharp pains, I think I was told it was stretching and stuff, nothing to worry about, worth checking with your OB when you see him, but I bet that's what it is.