anger is getting out of control

I have never been like this in my whole life, I am not an angry person at all. But every time my colicky baby cries I just want to hurt him and make him stop. Every time I'm holding him and he cries, my arms get tense and I feel like shaking him. Which I know is really bad for babies but I need to get my anger out. I cant leave him to cry while I relax because once I calm down a bit and go back inside to get him, he's still crying so my anger hits the roof again. I feel so bad and can't talk to anyone in my family as they don't see depression as being serious. I have only been feeling this way since I had my son😢 I'm scared to go to the doctors, I don't want them to think I am an unfit mother or hurting my baby. I'm not good at expressing my feelings to people😩 please tell me I'm not the only one going through these anger feelings towards my baby. It's getting really bad😩