Is it okay for my doctor to do this?

I went for a routine check-up, and my results were great. Even my doctor said so. But she told that I'm slightly underweight, but it's not affecting my health in any ways since I'm perfectly healthy and I'm not dieting or restricting any food intake. My body is just made this way. My doctor gave my number to an eating disorder specialist, who keeps calling me and leaving me voicemails, telling me that I'm anorexic and I need help. What should I do about it?
Is it okay for my doctor to do this?
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