Is the formula you are using milk-based or soy-based? I try to stay away from the milk-based formulas as they can be extremely constipating. You might want to make sure that every bottle he has, has a dropper full of the Kid-e-reg in it. Also, don't worry about solids yet - he is still pretty young. I would make sure he has, at least, one bowel movement a day - even if you have to use the suppository to get it started. You don't want those toxins sitting in his system - it will only build an environment for disease. Along with the prune juice, I would recommend drinking some fresh apple juice each day. In fact, instead of the formula bottle, you might want to try some diluted apple juice with the Kid-e-reg in it. This should help to promote parastalic action to move the waste through. Also, make sure that your diet has plenty of roughage in it (in the form of fresh salads and fruit), so that you are passing it along to him. Good luck and keep me posted.