He'll wee in the toilet/potty but needs a nappy on to do a poo.
I know what you mean, my son was very similar. All I did was the usual tricks to encourage him to poo on the potty (lots of encouragement and praise, bribery etc), and I also gave him syrup of figs every night for a couple of weeks to get everything moving in the right direction as he had been holding it in and it had become quite hard. I also tried to give him plenty of fruit and water for the same reason. Do you take him with you when you go? This seemed to help 'de-mystify' the event and show my son it was nothing to be frightened of.
I know some people have tried using a nappy but with the child sat on the potty, and then cutting a hole in the nappy so it drops through into the potty, then going without the nappy altogether.
Hopefully, it's just his bad experiences when he was poorly that have knocked him off track a bit and he'll soon return to using the potty/toilet for everything.
Good Luck XX
How about trying a different rewards system for poos? Like giving a smartie or something else small whenever she does one in the potty/toilet? I think that was Theoldwomanwholivesinashoe's idea and getting an immediate treat did seem to help...
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