What Causes Metallic Smelling Vaginal Discharge?

I had sexual intercourse 5 weeks ago. My vaginal discharge had changed about a week after that. it was kind of thick and white. there was no fishy smell but it did have a different smell. it smelt metallic. About 5 to 7 days after sexual intercourse my period came. It was about average. Though i have felt a little odd lately. I started to show signs of pregnancy so i took a pregnancy test. It came out negative. I again had another period it lasted 5 days and ended two days ago. but today on my toilet paper there was a little fresh blood on it. yesturday i didnt have that problem. I took another pregnancy test and it said negative again but the second line that would tell me if i was pregnant was VERY faint idk if that meant anything.... My vaginal discharge still smells metallic but not as much white discharge as usual. what might be wrong?