being pregnant while you have a toddler?

Desss
I'm currently 16 weeks with my second child and I already have a 9 month old. He's really rough and always throws his head into my stomach when he doesn't get his way. It's frustrates the hell out of me. It's gotten to the point where I have become distant to avoid him falling or kicking on my stomach. I have yet to felt the baby move this pregnancy so it worries me when the constantly does this. I don't want to go as far as spanking him because he's a bad and doesn't understand that I'm pregnant. But it's frustrating!!!! Is there something that I could do to avoid him being so rough? I hate that I can't really play or cuddle with him because he's too rough.