Some douche keeps DDosing my internet connection. What can I do?

I run a Minecraft server (which is my main source of income) on my computer and sadly can't afford a host. This guy keeps DDosing me and I'm getting fed up with this.

I can't afford DDos protection either.

Is there any way to stop him from DDosing me for free?

Call the police or your isp or their isp

Well you can talk to your isp and they should be able to put a block on the attacker at their level.