Let me add to that: I don't always have problems with mixed gender, genital examinations.
But there must be relation of trust and respect between doctor and patient.

In the past I had a female doctor examine my penis.
She was also young, just a few years older than me, but I knew her, she was my doctor for some years and she was a very caring and respectful professional, I did not feel awkward at all back then.
If anyone felt a little awkward it was her, and I admit I am quite the pervert, but I behaved perfectly, because I did not want to make her feel awkward or disrespect her.