Aggressive strange behavior 5 year old

My nephew always shows signs of SOMETHING! i have no clue what it is... He's 5 years old now, and ever since he could sit up by hisself he's been behaving strangely.. He would bang his head on the floor, and try to bite and hurt others... He's never had a learning problem, he's intelligent, he talks very well... But for him to behave is extremely far fetched... and it is always a surprise if he does act good. Ever since he's been potty trained his played with his poop, either putting it on the walls or on his brother and sister... He has always tried to harm his siblings and his little cousins... And when he gets in trouble it just makes him madder, and act out more.. his mother refuses to get him evaluated because she doesn't, "believe" in mental disease... i think his problem stems farther from just add, or adhd.. He is very hyper of course... but he is just very mean, and doesn't like compassion.. he doesn't like to hug, or be hugged... he holds no sentimental value to anything.. he's very detached.. he has no close relationships with anyone, yet if he doesn't get attention he acts out, and purposely does bad things, as if to seek attention that way... whether it's positive or negative.. though he seems to do things to get negative attention, more then doing things to get positive attention... almost as though, he doesn't like positive attention... just today he peed on his little brother, and laughed even while he was getting in trouble.... my sister is going to lose her mind if something isn't done.. and i don't know how to convince her to get him seen about..

[Sandman2]

      It may be hard to get anything done until he enters the school system and they start making referrals.  It is sad that his mother doesn't see the need for help because what he is doing is not normal.   The problem is that there are a lot of ways to help kids (without meds too).  In fact, the public school systems will evaluate kids early so that they can start getting help before entering the school system
     Some of what he does sounds like sensory processing disorder.  Here is a site for info on that - http://www.sensory-processing-disorder.com/.    This is something that can be treated by an occupational therapist (no meds).  It is not a mental disease, but a condition of hyper sensitive nerve conditions.  And, of course, he also shows some signs of Autism as well as ADHD.  But, I think, the point is that his actions are in response to how he is reacting to the world around him.  You can't help him until you figure out why he is feeling this way.   The longer mom waits, the harder it will be for him to live a normal life.  Good luck!

[concernedbystander]

Thanks so much... i've googled this poor child repeatedly and have came up with so many different things that it could be... and unfortunately he is in the school system, but it's a very small private school with only about 50 kids grades kindergarden through 12th!!! She keeps claiming to be at wits end, and going to have him seen about, but then it just never happens... and she gets very upset when people try to press the issue even in a nice way... but she is struggling with problems of her own as well, that none of us know how to deal with so... they're just heavy on my heart... i wish i could do more to help them.

[Sandman2]

    How does he do at school?  If the problem is only at home, there are behavioral methods to help him.  
    Actually, if he has problems at school - and they are real problems.  They may not be able to deal with him (typically, small private schools don't have the resources) and may not accept him the next year or expel him this year.

[concernedbystander]

He does okay in school... but he does sometimes get in trouble for hyper activity or being mean to the other kids... but i don't know exactly how he is in school, because my sister doesn't like telling stories of him getting in trouble.. i do know on his first day of school, they were already calling home saying that he was refusing to do his work, and wouldn't listen to anyone.

[gitsum]

send him to a professional that specializes in these sort of things, and also send him to a religious figure such as a priest or pastor.