"Potty trained" 4 years old suddenly going backwards!

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My four years old has been out of diapers since he was 2.5. We have had some pooping accidents before, but I feel like that is a normal thing to happen. The last month or so however, he poops his pants almost every time. He has even peed himself and on the floor a few times. He has also pooped in his bath two times and he has never done that before, not even when he was a baby. I've called his pediatrician several times and they say it's normal, but I feel like it isn't. The hospital refuses to see us because they are over full capacity with corona patients, so they only accept urgent cases. I get that. We live in a very rural area, so I can't call another hospital or pediatrician because there is none. We are not in the US.

Nothing at home has changed. We've been quarantined since March due to me and son being in a risk group. I'm a stay at home mom, and except for my husband we are the only grown ups he is alone with (I've read on here so many times that accidents can be a sign of sexual abuse, but this is not the case here). Besides the accidents he is happy and well. We do a lot of activities and he has a little brother to play with, so he shouldn't be bored. I've started doing potty routines, as in he gets to read a book or something on the potty about 20 mins after every meal, but it hasn't changed anything. It's like he doesn't care. I don't make a deal of it, we clean up together and I tell him we use the potty or the toilet. What is going on? Is this really normal? What should I do?