Knot in belly 10weeks and 5 days

Ok, I'm not a person who sleeps on my belly but for the past few nights I have and when I do I wake up with a feeling of a little knot or bulge on the right side near my pelvic bone that's a little tender so I roll over and very lightly and gently rub it and it disappears and the tenderness subsides as well! Has anyone had this? Could it be the baby favoring that side while I'm sleep? I had a pelvic exam yesterday and nothing abnormal! You can't see it when I turn on my back, it's just a feeling of something is there and it's just a little tender!