How long can a custodial hold on to college and medical expenses aND ask to get reimbursed. The divorce decree did not even touch on that issue.

As a general rule in Indiana, you do not have to pay for college expenses unless there is a court order requiring that you do so.  That court order may be in the Final Decree or Settlement Agreement or it may be in an order modifying that final decree.  If the initial child support was ordered prior to July 1, 2012, then your ex-spouse has until your child's 21st birthday to ask the court to order that you pay college expenses.  The court may or may not make the order retroactive back to 2011.  The issue of your daughter not responding to you is very fact sensitive and a court may or may not take that into consideration in determining whether they should order the college expenses paid by you.  The court will consider the reasons why the child is not communicating with you in making that determination.   Medical expenses are generally ordered as a part of the child support order.  Generally, the custodial parent is required to pay a certain amount each year of the uninsured expenses and the remainder of the uninsured expenses are split between the parties in proportion to their income.  It would be very unusual for a child support order not to address the issue of medical expenses.  I would go back and carefully read your divorce decree and any child support obligation worksheet which was attached to it.   These are complicated questions and there are many other factors which influence a court's determination of these matters such as the parent's respective incomes, children's grades, quality of the proof of the expenses, child's application for financial assistance, financial assistance, etc.