Argh!!! Why does my grandma think she knows more than a doctor?

I just got back from lunch with her. She was sick on my bday. Then I was sick the day we were supposed to go out after that. She tells me that my mother probably gave me the cold after being around my brother's sick girlfriend. I told her I had a sinus infection not a cold. She tells me I am wrong because by the way I sounded when I called her Thursday to cancel dinner she could tell it was definitely a cold. I explain I went to the dr on Thursday and he said it was a sinus infection. She told me I needed to find a new doctor because mine evidently doesn't know how to properly diagnose. WTF?!?

She also told me that I was jeopardizing my health eating dairy while on the antibiotic because it reacts with it causing toxins. Ummm...when I mentioned to my dr that antibiotics usually give me diareah, he said it is because it kills the good bacteria in addition to the bad bacteria and that eating things with probiotics like yogurt helps prevent that. Why would he say that if dairy and antibiotics were toxic together? I think I trust the doctor more than my grandma even if he is relatively young for a dr. He has more education than her. She dropped out of high school to elope.

I get so frustrated when family think they know more than drs and try to tell me things that are off the wall.