This is entirely from a massage therapist perspective, other professionals may mean something different if they ask you these questions.
As an LMT, I consider you to be under a doctors care if you see them for more than just an annual routine physical. Or if there are circumstances that could lead to a visit at any time, such as a medication you are on or symptoms that they are investigating. Also, if you are on a medication, we would consider that medical treatment.
Why? That condition (sometimes that medication or one of your symptoms) could change the way that we do our job as massage therapists. Maybe there are techniques that we shouldn't use on you because of your illness or medication. Some illnesses in certain stages would require us to not give you a massage at all, for your safety or possibly for ours.
Please, tell us everything. Your session is completely confidential and the more we know, the better we are able to help you.