Um, most of the medical professional bodies in the world would consider it professionally dishonest to offer any form of medical advice as a Doctor whilst hiding behind anonymity, and would likely start disciplinary proceedings over this.
Why would a medical body would have problem with a doctor - who doesn't use his title or name - that posts info on a forum ? he isn't deceiving people in any way , and he isn't using his title in a wrong way.
Unless the NSA is one of those professional bodies, you can probably stay anonymous on the Internet successfully.