Didnt Ask For Child Support From Divorce

I live in South Carolina, and I won full custody of my two sons, ages 5 and 6, about two years ago, and did not seek any child support. At the time my ex had no income, and I was doing quite well, but times have changed I guess. I could really use a little extra for the boys each month, as we are sometimes struggling to cover monthly expenses now. Am I able to seek support this late after the divorce?