Hun, weetbix are a "medium fibre" food and should usually be ok. You might need to try it again to see if it was a one-off or not.

The other thing to consider is that constipation can sometimes be a sign of a food intolerance. This can be pretty tricky to figure out, but I guess if a good diet and plenty of water isn't doing the trick, then it could be worth talking to a dietician about trying an elimination diet. There are dieticians who specialise in food allergies and intolerances, so I would be looking for one of them. You can do a search on the DAA website - www.daa.asn.au - by specialty.

All the best with it. I have a 5yo who still has big issues in this area (and yes, we have resorted to meds too, so I do understand your position!). I really hope you can get it sorted quickly. It gets much harder as they get older.