Toddler constipation

[JJazz21]

My lo has been constipated since weaning onto food at 6 months, she is now 2.5 years and has had to take laxido every day for 2 years, I really thought it would have gone by now as the doctor said their bowels change somewhere between 15 and 20 months and that should sort it but nothing has changed!
Just wondering if anyone has been through the same and if you found cutting any foods helped? Or if there was an underlying issue?
I’ll be taking her back to the doctors soon but wanted to go with a bit more knowledge than I have now so I can push for answers!
I have taken her to the doctors in the last 2 years a few times but been brushed off every time

Could be milk or gluten? Maybe adding prune juice or creamed spinach to their diet in the morning. I have ibs and as a toddler I would struggle with milk. Now that I am meat and mainly dairy free I rarely have issues. I'm not suggesting veganism at all though. Also bananas can cause constipation.

We’ve a nearly two year old with constipation since weaning if unmanaged. She has pears or prunes twice daily (won’t eat them fresh so we give 2x Ella pouches) which have made a massive difference. We avoid bananas too

My 2 year old daughter has been using Nutrigen Inulin, which has made a big difference

My son is nearly 5 and suffers with constipation. He is on movicol once a day in his juice and if really softens up the stools. He is scared of using the toilet though and pooing so this doesn't help as he will hold for as long as possible. Will only poop in a nappy too. It's a nightmare and I hope one day he will grow out of it x

I think movicol is the same as laxido, my 2 year old will have 1 sachet a day and it does usually work however since having a loaf of white bread instead of brown it’s made it worse even with the laxido, which is what has made me think it could possibly be wheat / gluten.
We are lucky that she will poo on the toilet but if she gets constipated again for whatever reason it will hurt her to poo (anal fissures) so that’s when she gets scared and has accidents.