Great question, and I am sorry you have been unable to locate the appropriate physicians. I am giving you a link HERE that will take you to a website called Maine Citizens for Patients' Rights. They are the custodians of the database regarding medical marijuana. Currently, there are only two physicians in the state who are willing to advertise publicly that they will consider patients for medical marijuana (one in Augusta and the other in Hallowell). However, the website does indicate that there are dozens of other physicians in their database who have yet to grant permission to publish their names and locations - but the website will be happy to provide them privately if you contact them directly (contact info. also provided through the link). If there is not a physician specifically in Waterville, I am pretty sure there will be one close by.
I think you will find exactly what you are looking for here. If you are satisfied with the response, please hit "Accept." That is the only way i receive credit for my answer. Thanks-