How do I get over feeling depressed at the doctor?

I know I will sound like a big baby but I truly hate having to see a specialist. My primary care doctor isn’t a big deal. But being sent to a specialist just puts me into a depression when I go there. I always feel I will be given bad news. Other than this, I’m usually a happy person. The day before going there just gets me so down, way down. And I haven’t even found out anything yet. Usually it turns out okay but I wish I could stop feeling so depressed when I have to get blood test to see what’s going on. I always feel like I’ll hear the worst, though thankfully I haven’t yet. Why do I keep doing this? And I’m much worse at the Dentist. It just gets me so down because it hurts even when they claim to be a “painless dentist”. I am so depressed when I have to get dental work done. I feel it’s nothing but a torture chamber. Plus the expense of it gets me down more. I wish there were no such things as illnesses or problems with our teeth. Life is hard enough without having to be put through the depression and worry over blood test and also having to suffer at the hands of a Dentist. Any suggestions would be really appreciated.