Work and doctors appointments

Anyone having issues with doctors appointments? I work mon thru friday 7am to 4pm.

Im always having to leave early one day evey 2weeks. Only an hour or 2 early. With which what i do i am able to and its no big deal and my boss will let me make up some of my time by coming in early or something. There has never been a problem with it.

Now i have an appointment coming up on friday at 1pm. And my dr doesnt have any later appointments cause she is on call. I didnt know about it until obviously the new schedule at work was posted since i go every 2 weeks now.

Now my boss is saying i cant make up anytime that i just have to lose the time. ( i usually would come in an hour early a couple of days to make up the difference and i am always almost a day ahead with my work). My manager above her last week ( she was on vacation) told me that it was fine for me to leave early and makeup some of my time.

Shouldnt my boss have told me that last time ? Instead of waiting until after i made the appointment. Yes i know i should make them for after 4pm but my dr never has any available at that time ( she is always on call on my available days of thurs and Friday doe appointments) ) and it has never been a problem me leaving early until now.