A.
He had a big change just like mine did when we got him potty trained. He left daycare which was a huge part of his routine and schedule. He is probably just trying to adjust and get used to not being in his normal routine. My son had a baby brother come home 3 months after we got him potty trained and guess what? He magically forgot how to go again. After talking with him getting on to him making him sit on the potty chair he finally asked us why does the baby get to go in his pants & I have to go in the big boy toilet?
They are pretty smart and some times all it takes in finding out what is going on in their little heads is to just ask them and try to be consistent and maybe when he gets adjusted to being out of daycare he will once again be in a routine for potty training. I know when I was on maternity leave part of it was the babysitter had SET times they all went to the bathroom as a group after snacks, Lunch, and active playtimes and that was what motivated him was everyone else was using the potty too. I didn't know when her "Potty times" where and had him home for awhile just long enough to mess his world up for about 5-6 months after going back to her house it took us to get him RE-potty trained especially with boys you do not tell them when to get potty trained they tell YOU when they are ready. The little girl at the babysitters was potty trained 2 months after her second birthday. My son at around 4 years old & my friend with 5 boys around 3-4yrs old too. Girls catch on MUCH faster in potty training I am told. I am getting ready for round 2 here in a few months with the baby so looking forward to it too;)
It will happen just give it time no child starts school in diapers
Good luck