Help! My 15 mo son has been an excellent pooper his whole life - we sit backwards on the toilet every morning, him on my lap, look at books, and he poos. No pressure, no discussion even, just our routine and easy as pie. UNTIL we went away for a weekend a few weeks ago. He did not like the toilet there and would not go, which has happened before on trips. But when we got home, he no longer wanted to poop on the toilet. He will still sit with me and look at books, but he will not poop, and eventually gets down without getting to business. He now goes once every few days, and when it happens he is FREAKED OUT. He goes around on tiptoes whimpering and obviously trying to avoid the whole thing. If I pick him up to put him on the toilet or the little potty or the toilet with an insert before the poop is actually coming out of his butt, he arches his back, screams, and then sometimes won't go for a few more hours. If I do nothing and let him poop on the ground, he freaks out crying, yelling poop. Then even if we got it caught at the last second, he will not go any more, but then 15 minnutes or half an hour later, he goes again. The whole cycle usually repeats several times and then he won't go again for a few days.
I have known for some time that we were beginning to outgrow our old position - his legs are so long now that it can't be too comfortable (and I have barely any room to sit behind him) but my attempts to transistion to a little potty, bigger little potty (2 of them), and insert all went nowhere.
He is also getting molars, which do not in themselves seem to bother him much although he is nursing more at night.
Any thoughts on how to help this go easier for him would be much appreciated!