ocd or normal behavior

I have a son that will be 3 in Sept. He has been extremely difficult due to his behavior. He had several health issues the first 2 years of his life, RSV (he was hospitalized both times) and he has his second set of eartubes and is currently getting speech therapy. He has always had to have things a certain way but lately things just seems more odd than ususal. When he takes a bath you have to undress him in a certain order. If I try to take his shirt off before his socks he has a meltdown. Before he falls asleep at night he will grab his blanket and have to grab all 4 corners and rub them. And for the last month he ONLY wants to wear yellow shirts. I have had to hide all of his yellow shirts because if he sees them and I try to dress him in something other than yellow he will fight you when you attempt to dress him. Now I will admit, due to him being the youngest of 4 and due to him being sick so often, we did tend to spoil him a little more. I don;t know if his behavior is normal for a 2 year old or if there is a problem or if we created this behavior. He hits his brother constantly. He will go into a rage where no one can get near him and 15 minutes later he is the sweetest child you can imagine? Is this behavior something I should be concerned about or will he grow out of it? Thank you.