This sounds like what I have, the midwife has called it 'symphis pubib dysfunction' (maybe google it to find out more) I'm starting physio next week for it- yes bending and sitting on the floor make it much worse, and sometimes going down stairs sets it off and getting up for a wee can be difficult. I'm hoping they get me a belt which I think will really help. I'm not really worried about the pain as it comes and goes when I do certain things but I am worried how it may affect the labour as stretching in different positions will be hard, so hopefully an epidural will be good, but I need to disscuss it with the midwife.
I would call your mmidwife hun just to let her know what's happen, a belt or something may prevent your back from getting worse, and its good for them to know these changes for when you go into labour xxx