Serious question I need help with

So I have a 3 year old little boy and his temper tantrums are unlike any I have ever seen before. He screams hits and kicks. It’s almost like he blacks out because there is no calming him down. The other day we were at a store he wanted a toy and I told him no and he screamed for more than an hour. Kicking hitting biting and throwing himself around the car and eventually he calmed down when I took him to the park. He responds to me but ONLY ME. I have an older son and my 3 year old will kick bite and slap him if my oldest doesn’t do exactly what he wants him to do. He literally screams if he can’t do something and forces someone to do it for him unless he will hit and throw things. I don’t know how to explain it but this isn’t normal behavior. He is verbal and very smart he hit all of his milestones so I don’t think it’s autism I just don’t know what the issue is... any moms experience this? Please don’t say it’s normal I have 4 kids this is not normal I’m really scared because I don’t know what to do to help him. The earliest appointment I could get for him was in July I need some advice.