My 2 1/2 year old son has a bloated tummy most of the time. He was 35 1/2 lbs at his 2 year checkup. He has always been chunky since 6 weeks old from breastfeeding. He eats healthy meals and snacks during the day. Everything else seems to be normal.
Dear parent if the child is happy, eating paying growing well passing urine and motion normally then I don't see any reason for concern. If he has too many gasses, discomfort or constipation or lose motion then you can take him to a pediatrician otherwise be patient and happy.