I was going to say that we're required to use PTO and floating holidays for medical visits because this is America, and our benefits are way below many other first-world countries.
Yup. Although in my company, you can sometimes use a sick day for something like having a procedure where you'd be given anasthesia. I was told I should have done this (after having such a procedure, having complications and then being in the hospital and out of work for 2 weeks), because then it all counts as sick time, then STD.
My boss is also pretty flexible on that as well; a couple years ago I had a dr. appt, figured I'd be out, and then come back. Nope. my dr. ended up sending me to urgent care, where I spend the better part of the afternoon having tests, and being diagnosed with asthma, so that counted as a sick day. But everyone is different.
Good for you, and no, you don't need to feel guilty. You're at the dr., regardless of what its for.