My 3 year old's behaviour has changed drastically. What could it be?

My son is 3 years old, will be 4 next month. He used to be so well behaved, and caring. Now im challenged with potty training again. He deliberately wees on the floor, when he is right next to his potty. He uses the big toilet fine in nursery. He refuses to wear clothes in the house, he is always naked, and I am noticing he is ''playing'' with himself alot. He will not sleep in his bed no more, he will get up in the middle of the night, take off his pj's and sleep naked on the floor wrapped up in his duvet. His appetite has also gone in the past few days. He is now fascinated in washing his hands, upto 20 times a day, Ive had to lock the bathroom at times. I do not know why he is acting like this?? I am pregnant (4 months) and wondering if the baby could be making him act out. Im also going through a nasty court battle with his dad who I left when my son was 8 months old due to domestic violence. His dad has wrongly accused me of neglecting my son. My son sees his dad every fortnight for 2 nights. I am hoping that he or his girlfriend are not causing this bad behaviour. It has started around 3 weeks after my first court date and been going on for 2 months. I really dont know what to do, ive tried spoiling him, using disiplin, nothing is working.