Transformed migraine is now often called chronic migraine. It occurs in patients that have a history of migraine. Over the years, attacks become more frequent, until they end up with something similar to chronic tension-type headache. They may or may not have migraine attacks like they used to – just this daily or near daily background headache. If this is you, you probably actually are getting mild migraine attacks, not tension headache at all.
The causes of these headaches are different with everyone, but it’s important to know which you have in order to be treated. Generally, you won’t be "cured" of your headaches, but they can be very much reduced. In the case of transformed migraine, many sufferers have a form of rebound headache. This means that painkiller use can be tapered off and the headaches can taper off as well. But there can be other causes as well, such as a virus or a drug you’re taking or food you’re eating.
Other types of chronic headache include Hemicrania continua (a one sided headache usually treated with Indomethacin) and new daily persistent headache(typically in patients with no history of headache).
Both these headaches are of the kind that you need to see a doctor about. Make sure she knows your medical history so that an accurate diagnosis can be made.