It will depends how much your ex made and is making.
If he made tons of money from the stock, you should consult a lawyer who is very good at this kind of thing.
If he just made decent money and is having decent income, from what I read from this forum, you can ask judge for child support adjustment.
If he is a reasonable person and cares about his kids, his income is pretty good, and you don't want too much trouble, ask him to setup a college saving trust (or 529 plan or UTMA) under your kids' name.