Potty training advice needed ( almost 4)

My son is almost four year old, he keeps regressing on being potty trained we literally have tried everything. He will randomly pee himself during the day and at night he pees himself in his sleep. We have tried putting him in pull ups at night. But we feel like him using them just makes it worse during the day and he has more accidents if we put him in one suppose to just underwear and waking him up at night to use the bathroom. The frustrating thing is 6 months ago he was completely potty trained. We moved to a bigger place and before getting our new place we stayed with both grandmas. Maybe a little over a week . Now no matter what we do hes still hasn't stopped having accidents since we moved into our new place. * more detail i have kids from a previous marriage and I moved in with my mom and lived with her for a year until I got my own place. I met my spouse and we had are fair share of epic fights in the beginning of our dating so she dislikes him. She had a problem with him disciplining and being a parentel figure when we got serious. ( during my childhood she remarried and chose her husband over myself and bother he was super controlling of everything and abusive, we weren't allowed to watch TV with permission ect. Basically hide in our rooms until we were of age to move out) I feel she still has regret with that so she's trying to make up for it with my kids. When she would watch them in the beginning she wouks tell them if he disciplining or ask them what my spouse would say or do ( we spank on rare occasion) . She Basically told my kids not to listen to him and only myself and her. It caused alot of conflict and fighting between all of us. So when I got pregnant and he took full responsibility of watching the kids while I worked she lost her marbles and tried to acuse us of mistreatment of our kids. We didn't see her much after that. I distanced myself from her because she was respecting our boundaries. She had a key to my apartment and when my spouse moved in she would pop up on random visits to check if the kids were okay ect... My old apartment was in a bad neighborhood and the management was worse. Before the lease was up we moved out due to repairs needed to be done but they never came. The last straw was vandalism on our car and the toilet tank pump going out and the management refused to get back to us. Before we got our new place I tried to stay with my mom with my kids and my spouse not getting along staying with his family. I didnt stay long due to my mom constantly underming me stating her house her rules. So whenever I tried to parent she would step in a spoil the kids. My kids call my husband dad and she has a problem with that and tried to get them to call him but his real name instead. Always using it instead of dad when they talked or brought him up. ( I lasted 3 days) and decided to camp in the living room of my hubbys moms she only had a tiny place where my mom had a room for the grandkids. We stayed about a week until we found a better place and better area. But since all the moving and house hopping my son has issues on going to the bathroom. I dont understand and I need help.