Help with a 10 month old rescued Mallinois/lab mix !

We rescued Max nearly 3 months ago and he was fine, he had the odd accident in the house, to be expected with his age and the move and then he settled down.He trained very quickly to pee and poo in the same spot and he has 4 yr old golden retriever "sister" to copy!!
Over the last couple of weeks he has really regressed, he is pooing in the house nearly every night at around 1am !! we have tried crating him at night ( which we have never had to do till now) and he still pooed in his crate,when he wasn't crated he was waking us several times in the night and each time either my husband or I would get up and let him out and we would still wake in the morning to find poo in the house!!
Can anyone help us and giive us some advice on what to do?