It probably is just a foot ... ah the joys of being pregnant! But just in case it is something more serious, pain on your right side at the top of you abdomen near your ribcage can also be a sign of pre-eclampsia. Usually it is coupled with high BP and protein in your urine (which most GPs and Obs check for routinely at appointments) but it might not hurt to mention it to your GP or Ob at your next appointment just in case it is something a bit more serious than just a foot.

Sorry to rain on your parade a bit ... it sounds like it is just a foot, but I wanted to put this out there as a possibility so you have all your bases covered.