Last year I hurt my shoulder pretty bad during a set of bench presses. My conversation with the doctor went like this:
Doc: How did your hurt your shoulder?
Me: Doing bench presses.
Doc: Were you seated or lying down?
Me: Lying down
Doc (wiggles my arm around): You tore your supraspinatus tendon.
Me: How long will it take to heal?
Doc: depends on how bad it is. If it takes a few weeks, it was a small tear. If it takes a few months, it was a bigger tear.
She refused to take an xray, and told me to lay off upperbody training until it was healed. As you can probably guess, the pain subsided when I started pressing again and went away completely when I started pressing heavy.
At my current unit, I had to fill out a medical questionnaire where I admitted to drinking protein shakes and consuming dietary fat on a daily basis. The doctor tested my kidney function. When the my kidney's were determined to be fine, she told me, "You're very lucky. I had a patient who drank protein shakes once and he had bad kidneys." She also warned me not to consume dietary fat every day. This woman was not just a professional doctor but also outranked the commanding officer of the base.
It's a pretty bad idea to take lifting advice from someone who doesn't know what a bench press is, or diet advice from someone who thinks that protein and fat are terrible for you. Doctors learn something in medical school, but you can't trust them on everything.