In the UK, the Royal College of Physicians is a national body/membership organisation that represents doctors - providing examinations, government lobbying, research, professional development training and support, conferences etc.
What would be the equivalent body in your country?
In Canada, the equivalents would be the various Colleges of Physicians and Surgeons (one in each province; name may vary; link takes you to the Ontario College), and the Canadian Medical Association.
The difference is that the Colleges are regulatory bodies - they don’t represent the doctors, they are the self-governing regulatory body. They set the professional standards for doctors to enter the profession and remain certified, and they respond to allegations of professional misconduct/incompetence. Although they are self-regulating, they do so on behalf of the public.
As such, the Colleges don’t lobby government on behalf of doctors. That’s the function of the Canadian Medical Association, which is a professional association to represent the interests of doctors.
So, a question - is it the case that the Royal College in the UK does government lobbying on behalf of doctors? from the Canadian perspective, that would be a conflict of interest - that’s why in our system there are the two different sets of organizations - one to regulate, and one to represent.
Probably the American Medical Association in the US. This is not a regulatory group; it’s a voluntary membership group that offers the sorts of services mentioned in the OP. (For instance, if a patient had competency concerns about a doctor, he or she would go to their state’s professional licensing board, not the AMA.)
There are also multiple specialty-oriented groups like this, but the AMA is the big generalized one.