I just went to the dr today today with the same symptom (tender belly bottom - feels like muscle pulling). She thinks its just tissue being pinched in my belly bottom (some belly buttons have scar tissue that won't budge when the belly button is trying to pop out). She sent me to have an ultra sound - baby is doing fine & is totally unaffected :d she said if the pain doesn't go away - I may need to see a surgeon to have the tissue cut so it will have some give.

Did your pain get better?