Why do some doctors look at your private areas?

Doctors do that so they know you're healthy. I just had mine and she had me take of my clothes(including my bra),but usually she lets you keep your undies or panties on. She waited for me to change and she gave me something to cover my vagina(and I didn't want her looking at my vagina or my boobs). Then before she looked she asked me about my periods and how many pads I used in a day. Then she put her hand under the blanket and was listening to my heart( she had her hands on my boobs and it felt uncomfortable) but she wasnt looking at them,but then she pulled the blanket up so you could see all of my boobs and she just felt them to feel for lumps. I was very nervous,but I also know that she is a professional and she isn't trying to offend you in any way. She might peek down your panties too.