Health costs are medical bills not daycare, extraordinary costs may be things like summer camps, senior trips, or sports type of costs. You probably want to consult your lawyer to get the clearest understanding of this though.
Every legal matter is fact specific, and there are often nuances in every case. This is intended for comment only, and does not create an attorney client relationship.
"Extraordinary cost" is not a term of art. In the courts where I practice, that provision would be considered too ambiguous to enforce. It is possible, however, that it has been assigned more particular meaning in your state, or in the court that entered the order. To know for sure, consult with a local experienced family law practitioner.
Best wishes for an outcome you can accept, and please remember to designate a best answer.
This answer is offered as a public service for general information only and may not be relied upon as legal advice.
Have a lawyer look at your papers and advise. As the others have hinted at "extraordinary costs" could be anything--and it well might be defined elsewhere in your paperwork.
The contents of this post do not establish an attorney-client relationship. Any comments made in this post are general in nature and may not apply to the specific facts and law of your case.