The best thing to do is contact legal help. This matter will need to be taken to court. There a judge will decide what actions will be taken. If you have the child for the greater percentage of time then they should change the custody order. If they do this then yes you will be able to receive child support.

As long as he is listed as having sole physical custody you will owe him child support. If the children are with you more than they are with him then you should think about going back to court to modify the order. My husband was paying child support to his ex wife for their 2 children. There came a time when social services took the kids from her and placed them with us. The children lived with us having only supervised visitation with the mother all summer long and we continued to pay her child support. When we finally got our court date the judge changed the order for us so that she would be responsible for paying us child support but found us responsible for paying her every last penny up until the court date even though we had them 99% of the time for the entire summer. So my advice is always to go to court and do it immediately. The longer you wait the more money will go to him instead of to your children where it belongs.

The short answer is yes.

You should visit with the child support agency in your area.

If you are able you could file your own motion, support won't be owing until you have a motion on calendar. A modification works the same way.