you might try a credit agency. The ones that help you consolidate bills and make payments. They should have some options.
As John said you can ask the dentist if you could make payments but I suspect that the medical portion outweighs the dental bill. The only other suggestion is to just send what you can afford to send. Start with the lowest bill and pay that first. It might sound flippant but 5k is not a huge amount. I know it can seem like that but in the grand scheme of things hospitals and dentists have written off more. Not that they should mind you but they have.
Good luck.