Your doctor may have a duty of confidentiality depending on where you live. This means you can tell them anything, and they can't act upon that information without your consent unless you are a threat to yourself/others or are doing something very illegal.
When I told my doctor he asked me if I had made plans to CTB. This is important for them to know because if you have made plans already, they have authority to make sure you can't hurt yourself.
I would recommend you tell them all your symptoms and how you feel, because without this information the doctor will not be able to give you the help you need.