3 Year Old Son With Severe Constipation

[qldmom]

I have had my 3 (almost 4) year old son on a gluten free diet since he was 2 1/2 because of some behavioural issues that seemed to occur when he was on gluten. I am celiac and have quite a family history of it. However, because he's getting closer to school age I decided to have his blood work done to see if the diet is actually a necessity. I took him off of the diet for just short of a month before having the tests done. The results came back negative (IgA <5 U/ml; IgG <5 U/ml; IgA <4 U/ml) and the genetic testing came back with mixed results. The strange part is that since being back on gluten he has been extremely constipated. I had to give him medication all last week for the constipation and it has been causing him a great deal of pain, especially recently.

My question: is it more likely that the constipation is just from having something new introduced to his diet and his body is getting adjusted or is it an actual sensitivity to the gluten? At this point he has been back on gluten for 2 months and the constipation (although the worst now) started about a week after going back on everything. His behaviour hasn't changed a great deal, but in the past year he has been exhibiting some signs of ADHD or possibly ASD. I am going to have his iron levels (Iron 16 umol/L ; Ferritin 16 ug/L) looked at more closely as well as that was part of my diagnosis (iron deficiency anemia). I'm just trying to piece everything together and get a sense that diet is affecting him, but I don't want to unnecessarily put him on it if his results are showing negative.

Any thoughts on whether I should worry about putting him back on the diet would be greatly appreciated!