I had a new baby 2 months ago and he's been in and out of hospital needing surgery then getting very poorly and ending up in ICU. My almost 4 year old has been staying at his nanas on and off while this has been going on but this last week he's began to pee and poop himself. He's been toilet trained almost 2 years and never had accidents at all. Things are more normal now as we are home and settled in but my baby is still in hospital so we visit him a couple of times a day. I need some advice on how to sort this out
Get him checked for an infection. When that happened with ds he had a foreskin infection. Easily sorted. My GP said you should always have it checked out if they've been totally dry that there isn't a physical cause.
Another possibility is severe constipation. This puts pressure on the bladder which causes wee accidents. The child may also experience diarrhoea which is in fact "Bypass/Overflow Diarrhoea" around the blockage. My child had this and we had no idea he was constipated.
Yes take to GP to rule out medical causes. But it is fairly normal for small children to have potty training regressions when they have been under a lot of stress, so it could also be that. There's not much you can do to reduce the stress really so just try to make lots of time for him, don't be cross about accidents (but don't be overly sympathetic or provide lots of attention either), try to give as much positive attention and praise as possible about unrelated things, being aware this is hard on all of you!