Have you had unprotected sex? This is the main reason why girls are afraid of the doctor.
I used to have large amount of yellowish discharge before my period was to come but the odor was always neutral. After I had unprotected sex it started to smell differently so I went to see my doctor because I was afraid more if I am sick than what is going to happen during examination. I had STD and I was treated for it. It wasn’t that scary or big of a deal but it could have been. My doctor told me that if STD is left untreated can lead to some serious consequences and sometimes even to death.
My advice to you is to see the doctor. Your health is the most important thing and if you are old enough to have sex then you must be responsible for your body. I hope that it is nothing serious and that you are going to be just fine.