i get similar things as well, i asked my ob, but he said just ligaments stretching etc. i thought it could of been bh, but, also thought it was to early for me, was only about 15weeks when i saw him.
I think i posted a thread, and the general feedback was ligaments stretching, and confirmed by Alan, which i now take as gosspel!
Is the feeling between ligaments streching etc heaps different from bh?