Try adding essential fatty acids to his diet. Many problems you are describing are the result of an essential fatty acid deficiency - even the bed wetting. My 7 yr old has been taking a product called Efalex since May 1999 and 99% of his anger, misbehavior, and even dyslexia have improved 200%. A deficiency in DHA is the problem and supplementing with essential fatty acids can help in as little as two weeks.
If he is grinding his teeth at night then he has anxiety. My 7 ry old has problems with peer groups and social skills, and this may be his problem also. My son takes 25 mg imipramine PM plus I give him standardized Kava Kava at night also. You could try 50 mg B-complex daily which will help with stress.
Try reading "The LCP Solution" by Jacqueline Stordy and Malcolm Nicholl.
I am going through exactly the same thing. I have not been able to get any support on this, I always look like the one with the problem. My daghter is 6 now but this began when she was five, and she only does it to me. i found that if I do not react to the behave, and stay consistent with her punishment, she responds better. I have to get right in her face when she is having one of these episodes, and it seems to calm her down. It seems that it happens the most when she is not getting her needs met. I try to give her as much positive feedback all day, even if she does not seem to need it, like if she has not done something good, I will tell her she is having a good day, lets keep it that way, etc. Let me know if any other things are going on to compare.
Wioth most types of childhood problems, parents can manage the situation by changes they make in their parenting practices (e.g., communication, behavior management). Sometimes professional evaluation/treatment are called for, and the situation you describe warrants such assessment. Whenever young children are displaying problems across settings (i.e., not confined only to the home), it's more likely than not that they are manifesting signs of emotional unrest, not simply normal-spectrum childhood behavior problems.