3.5yo DS potty trained for nearly a year, back to pooing pants..ideas/advice?

[MistyGee]

Bit of history:
My DS is 3yrs 5m and has been fully potty trained (dry day and night, all poos and wees in toilet with occasional wet bed accident at night) since he was about 2 and a half. He has been great bless him.. until now - for the last week he has been pooing his pants daily.

Have been doing the old tricks I used when initially potting training - rewards for poos in toilet, reminding etc but apart from spotting him looking shifty and whisking him off to sit on the loo I have had no joy.

I have tried talking to him about it and asking him why he is pooing in his pants and not the toilet, but he's just vague and even this morning he said he likes pooing in his pants!! I am trying not to make too much of an issue of it.

We went on holiday for a week this yr and he was fine, the change didn't affect him toilet-wise. Have stayed away at both sets of grandparents - no probs. I was wondering if it is Christmas but we have been at home and no big disruptions or anything like that. He stayed with his dad for a couple of nights but he is close with him and used to his place and has had no problems pooing in his toilet before, plus I was popping in and out so I don't think that was the problem.
It doesn't seem to hurt him and he said no when I asked if it hurt so doesn't seem like a health thing.
This morning he ran into the kitchen and pointed to his bum and shouted in a happy voice "LOOOOK!" and seemed to think it was quite funny. There was also a wee in pants this morning with it. He hasn't been wetting or pooing the bed and ive been taking him to the loo regularly, although he usually asks and can hold it til put on toilet.

I just don't know what's going on. Is he doing this on purpose? Not sure how to handle it. He is due in preschool (currently goes once a wk) tomorrow, eek! I have tried saying that big boys use the toilet and that all his friends in preschool do and they don't poo in their pants, he loves going there...don't want to upset him too much though.
It is just so weird that he has regressed after nearly a year of doing so well. I have looked online but it seems to be to do with the inital potty training phase and regressing weeks not this long.
Has anyone had a similar experience? I'm not sure how to handle it. Do I ignore and just clean up and hope it is a phase? He is well aware of what he is doing and has control over his poos.. is there something i'm missing?
Sorry so long, just wanted to get the facts in. Would be so grateful for any advice Thank you.

[lucyandbeanie]

hi, i hope we do find some one to help my boy will be 3 in April,he has be great for 6months then last week out of the blue, he is jumping around saying "it's stinging" holding his willy, but when i ask where does it sting he reply's my bottom, took him to the doctors, just in case he had a urine infection but all clear, 4 days of him hoping around going to the toilet for a wee very frequently then poo arrives in his pants? spent 20 mins in loo at the museum today refused to sit on the toilet i managed to stay calm and tried to reason with him! only for him to poo 5 min's later in his pants the cafe - mummy had cold soup on return.
possible negative effects on him recently... Christmas was difficult my gran in hospital we did visit as a family and back to fairly new Nursery he does enjoy but makes a bit of a fuss when i'm dropping him off.
sorry i can't help you maybe some one will come to our rescue!