Hi Mellon
I think that a visit to the doctor is a good idea. However whilst you are waiting for your appointment try these tricks.
1 Lay your baby on his back and move his legs as if he is riding a bicycle, do this for about 10 minutes or so a few times a day
2 Wet the corner of a face washer, nappy or towel. Stroke his anus with the wet corner 6-12 times a few times a day.
You can do both of these tricks together.
One last thing. Make sure that when you mix the formula you are mixing the correct amount of powder and water.