Mucous, pale green, painful, soft stools

My 5 year old started having a change in his stools about 2 weeks ago, but then about a week ago he started complaining of abdomen pain and frequent bowel movements. His stools are slimy looking and usually pale green and very soft perhaps a few steps away from being diarrhea.He is an extremely picky eater and always eats the same types of foods, so his diet has not changed. He takes Flintstones vitamins with iron. I have tried Imodium (immodium) and it helps somewhat but eventually the symptoms come back and so does the pain. I thought maybe he had a virus or something because he has had a cough for 2months and his cough was starting to get worse again. He was put on albuteral nebulizer and that is when the pain started. He used the nebulizer maybe 3 days (got rid of the cough) and the pain started on the second day but has continued well past that. He has been on the nebulizer many times before and has never had problems with it. No fever, no vomiting. He seems to be ok in the mornings and early afternoon then as the day progresses it gets worse. I'm very worried because its not quite diarrhea it doesn't smell bad but its not his normal stool and when it gets bad he's always in the bathroom and in pain. The last time I took my son to the doctor with a fever and lots of vomiting the doctor did not examine him just said its been going around blah blah...I had to ask the doctor to give him a prescription for phenergan supp. I want to know what I need to do to make sure the doctor does what he needs do to help my son.  I believe that maybe my sons stool needs to be tested somehow. Am I wrong? Please help us.

[Renee Radenberg]

Suggest he gets checked by his MD due to the change in his stool and pain from medication.