More than 15 days a month is the definition for "chronic" with regard to headaches, though they usually also require some specific number of months in a row at that rate. Some insurance companies (you may have encountered this) limit how much Maxalt (or other abortives) they'll cover in a month, essentially telling you how many headaches you're allowed to have! (Sheesh!) Sometimes these limits can be overridden with the help of your doctor, but that's becomming tougher in some cases too - depends on the insurance & carrier.

Anyway, with that number of headaches, they'll probably also prescribe some kind of prophylactic:
http://www.migraines.org/treatment/treatctm.htm

This is where it could take some time, as it can take one to several months for some of these meds to become effective. They typically start you on the older (less expensive) meds, and work from there.

Another thing you could look into in the interim is if there are any foods that may be triggering these headaches:
http://www.migrainesurvival.com/food-triggers-2

Doc