Need advice about my 6yr old

My son is in the first grade and having more problems then he ever has! He's been to three different schools in the past two yrs due to us being military. His first two schools he had some problems in but nothing major. But this year it's a parents nightmare!!! He has slowly regressed instead of improving. He's not listening in class, will not do his classwork, talking to much.He even started lieing bout things and that's not like him. Until he started this year of school he has always been honest and not had a major problems with discipline. I got a phone call from his teacher this morning and was told he might have to repeat 1st grade. I know he doesnt like his school at all, well I dont either but I feel like we as a family are spinning out of control. Not only are we have problems at school but here at the house as well. My son comes up to my shoulders already and is half my weight. He's starting to push and trying to hit me. He does the same with his brother when he's mad.. I'm really lost and concerened about my son and the behavior. I've tried time out, taking thing's away, reward system,sitting down and talking to him and nothing is working!!! With my husband gone alot it all fall's on me and I'm breaking under all of this.