Try Nestles Good Start they are for sensitive babies. I had to put my youngest on this after her surgery.
Apple juice, White Grape juice, prune juice.... I used to get the green grapes and pill the skin off of them and feed them to my kids. pears are a wonderful fruit that will help clean the system out.
I agree with the posting on the Iron... Lower the Iron and you might be okay.
Mylcon drops (sp) in the formula 3-5 drops in an 8 oz bottle works wonders also.
Good luck... If you feel like there is something wrong and your doc says "aww the baby is fine." Just remember Mothers know there babies better than anyone!! I had to deal with a doc telling me everything was okay with my lil' girl at the age of 6 1/2 weeks old. She spent a week in the hospital and then had a major surgery done!
Stick to your guns!! If you feel that your child is sick or something is just not right bug the heck out of those doctors!!! I did and it saved my babies life!! :o)
Water is always a good thing for lil' ones. People forget to just give them straight water.
Good Luck!!