should we notify Child Support ? will it even matter ?

My SO got served months ago. Well we were fine with it. But now things have changed and My SO is not longer making all that Money he use to make at his old job. Which they let him go. Currently he works at Temps, basically when they need him. We arent married. And we got an Apartment as well w/ rent at $980 a month instead of the $400 he placed when we were renting a room at his Mother's home. Well now we got the amount he will have to pay which is $500. And that's basically almost half of my SOS checks. We arent married so our income isn't combined and he pays most the bills here. Should we notify Child Support and get a Lawyer to help ? Times have changed and now that is too high. The mom makes Double what he makes now. Im stressing on how we will make this work. With our new home and everything and now a whole check being gone.