Smells like dead!!😷😷

Hello!! I'm having a problem down there. It has been like this for months but back then it was just every other month but now it is every after my period. A brown runny and smells like dead discharge is coming out even without an intercourse. And it is worst when after intercourse. It smells like a dead rat. Can someone tell me what this might be. I dont think that it is STD because me and my BF are both our first time when we did it the first time. I do not use tampons. So if someone can help.. Please tell me because I'm afraid to tell my parents . I'm afraid that they will know that something already happened between me and my BF. I'm afraid that it might be a miscarriage and the some of the bloods did not all came out. So please help me..