My boyfriend had a personal injury lawsuit against him 20 plus years ago. He was ordered to pay $22,000 in restitution. As of now hes paid $28,800.00

I'm not 100% sure I understand you, because restitution is something that would be ordered in a criminal case, not civil, at least where I practice, but perhaps the terminology in IA is different.  If what you are saying is that your boyfriend had a civil judgment against him for $22,000 20 plus years ago, interest keeps running on the uncollected part of that judgment until it is satisfied (again, Iowa may be different, but I doubt it).  In New York, the rate is 9% annually, which is a big number.  After 20 years the judgment would have almost tripled.  Plus there can be costs incurred in collection efforts, some of which can be added to the judgment, such as marshal's fees.