If child support was waived in a divorce 3 years ago, can my ex now go back and seek child support

I divorced my ex in the state of Colorado 3 years ago. At that time the judge ordered joint custody on -one week-off one week. The child support was going to be minimal like $170 per month and my ex-waived his right to support that time. During the last 3 years he has moved 8 times. On two occasions for 3-4 months he had no residence and was staying with friends and in his vehicle so my daughter stayed with me for 3-4 months. I just started a new job and my daughter is not on my insurance now but he has her on Medicaid. It was court ordered we both had to have her medically covered. He is threatening to take me to court for child support. She had United Healthcare and Cigna until I started my new job. Please advise if he can now go back and get support when he has violated the court joint custody order on numerous occasions.