medical intervention, and perhaps religious counseling, is necessary. it may be hard to deal with, but it will only get worse. i'm not necessarily saying he needs medication or needs to be locked away, but he does certainly need to be seen by a doctor.
if he is a danger to himself or to others, then act right away.
I am sure this is so hard. I also think this child probably needs some help from a specialist given the trauma experienced in his early years. It sounds like you have done a great job, now perhaps he just needs that extra bit. I truly hope you don't give up on him. He's been through so much, and to lose his family again would be devestating. I wish you the best and hope you are able to work through this soon.
His reaction sounds normal based on what he has been experienced. Soiling and wetting pants, beds, things etc. is one of the normal behavior a child who experience trauma may develop, and may be an expression for so much.
In any case, it is important to show unconditional love for a kid who have been through such a trauma; learn him that he is worth as much as others and that he never should be afraid that he may be left again or abused.
Instead of being angry at his behavior you should change his diaper without question and go on without much negative emotions toward it; but instead encourage him to try to be clean and work toward him so that he can feel that he can experience care and love without wetting and soiling himself or his toys.
Such a process may take time; trauma recovery in foster kids often take some years with unconditional love from the foster parents, but it is cleary worth it as the kid's progression towards a good life would be much better if the young years are done right.
Also, can you get him a trampoline? I've recently seen lots of "buzz" about the positive affects of free play on trampolines for children.
I would start by putting him in clothing he can't get out of. and get a hospital bed warning thing (hospital supply store maybe?) that goes off with loud bursts when he gets out of bed.
It sounds like he had a really, really rough beginning and it may even be that he was born addicted to drugs. His behaviors may actually be caused by a brain anomoly, not by how he was treated.
But anyway, you can create clothing he is unable to remove, and start with that for bedtime.
Best wishes. This must be really hard.
I think this child needs help something is making him very unhappy..making a 4 year old clean up his'mess' is not good ..I would take him to the doctor as soon a possible