2 year old potty training help!! I’m desperate

Justice • son born 12-9-16👦 missed miscarriage 7-12-17 at 10 weeks👼 blighted ovum 2-5-18👼baby girl born 11-25-18👧

Hi there! I have a 2 year old little boy that I have been potty training for 4 months now. I have. 3 year old stepson that I potty trained at 2 and he was a breeze. The first two weeks were rough but he got the hang of it and now he’s easy takes himself never Has accidents except sometimes during the night if he drinks a lot before bed. On the other hand my 2 year old is another story. He wasn’t having accidents and told me when he needed to go. Then he started peeing his pants and telling me after, and now within the past 3 days he is peeing his pants and pooping his pants which he hasn’t pooped his pants in two months so I’m in shock. I did a reward system at first. I did praise. I ignored the accidents, I explained how we need to stay dry, etc. but he won’t stop and it’s getting worse and I’m losing my mind! I’m at a loss and I don’t know what to do. He used to wear underwear out in public and stay dry. Now he will just pee whenever even after I take him potty a few minutes before. I don’t know what to do!? He knows what he’s doing. We were almost fully trained a month ago and now we’re regressing so bad he’s starting to poop his pants again!? What the heck. Please help me understand what I need to do to help him get back on track and fully potty trained. I’ve been really relaxed during this whole ordeal. Do I need to buckle down and become more structured with this?