Bad luck. I hope it is nothing serious. Normally Airbnb expects you to try to gain recompense from your guest directly and it only steps in if you have made efforts but hit a brick wall with the guest. They will try to look at it independently and might not always side 100% with the host. But they will keep in touch with you. I've only really done this once with a difficult guest and once with an easy one who just paid me around 1000 dollars for burning my solid oak kitchen table (ouch!).
I suggest a week to try to sort it with the guest is about right and then escalate if you can't. Fingers crossed for you.