My dog is super grouchy and depressed?

my dog koda is almost 4 years old we got him from a pet store. ever since he was little he was kind of mean....so i spoiled him now that hes older he doesnt like people near me or touching me if my mom hugs me hell bark at her at first i thought it was cause he was trying to protect me but he does it to every one now to me my brothers and sister parents guests everyone. so we got 4 other dogs to keep him company 3 girl pomeranians kiah, kanieah, and koko and a chocolate lab hershey but he still acts this way to the point where my mom doesnt want him but hes my baby....what should i do??