Did you also take him off and then reintroduce dairy? Because dairy is a common cause of constipation.
Thank you for your response! I have never taken him off of dairy, but have just been doing more research that made me wonder whether that is something to try as well.
I guess the main impetus behind everything for my husband and I (aside from the new constipation problems) is his behaviour. He was in preschool/daycare for a brief period of time before I pulled him out because his teachers were concerned about his behaviour, noting what they believed to be prominent signs of autism. It actually came as a shock to us because he's always been a very bright boy, but social as well (in daycare he was completely withdrawn). We have since had him seen by different specialists and everyone has a different theory about what is driving his behaviour (adhd, asd, sensory motor issues). The problem is that it has always felt like everyone is giving a piece of the picture but he doesn't fit completely into any of the categories (as of yet - he's only 3). In addition, his behaviour fluctuates. He used to be a very focused little boy who picked up and learned things at a really rapid pace, and while he still picks up information quickly, that focus is rarely there anymore. He'll go through periods of difficult sleep (moves around a lot, wakes up a lot) which then makes him really restless and overtired during the day (he never allows himself to nap). I just find it weird that his behaviour is not consistent which is making me question diet so much. Along with the constipation at the moment he has also started sucking his hand and sometimes his shirt collar. There are just so many strange things going on...
I'm also curious about whether iron would help as he is very pale and can be so unfocused. I was anaemic for many years and never realised until I was an adult and my behaviour wasn't too dissimilar to his when I was young.
Sorry for going on about it...I'm just finding it all so puzzling at the moment (or maybe it is just the age?).