Severe behavior issues; at my wit's end

Forgive my grammar/spelling. My son is 5, this is his 1st year in school. Before this year he was in preschool, and had been in a daycare/preschool setting since he was 7 months old, so the school "structure" is not new to him. Since November he has had a lot of trouble in school and it has progressively gotten worse. Today will mark his 5th time this school year he has been suspended because of his behavior. He hits, kicks, cries, and screams at other students and his teachers and even the principal and assistant principal. It seems the only authority he cares about or respects is his mom and dad because this doesn't happen at home and we constantly go over what ours and his teachers' expectations of him. We have gone back and forth for months to the school to talk to guidance counselors and his teachers, his pediatrician, psychologists, and psychiatrists trying to get help for him but it seems nothing is working. He was diagnosed with ADHD and was prescribed a low dose of adderall but because my husband is very much against medication for children (and after a very long, tense discussion about it), we have not given it to him. I'm at the point where I don't care if he's on medication, I'm just tired of getting phone calls from the school, bad notes from his teachers, and suspensions. Although his teachers and counselors at the school all say he's very intelligent and is on track to be in the gifted and talented program, I'm afraid because of this he'll end up being the kid that couldn't pass kindergarten. Nothing has changed in our home; it's been suggested that maybe he's still having a hard time getting used to no longer being an only child, but our daughter will be 2 this year, and our son never had behavior issues of this severity before this school year. It's also been suggested that he's just bored in school because he knows everything that's being taught but boredom doesnt cause you to violently kick and hit and scream. I really don't know what else to do and am desperate because it's not only affecting our home life, but this has become emotionally draining and financially as well because we are having to take time off from work to deal with this. I just want my kid to get better and I don't know how or what else to do beyond what we've been doing.tl;dr my 5 y/o has severe behavior issues, all help that we've reached out to doesn't seem to be working, at a loss for what to do next via /r/Parenting http://ift.tt/2lTDGKP