Brown discharge

About two weeks ago my new boyfriend I decided to have sex we didn't have a condom since we weren't planning on anything that night, so we used the pull out method. I know that's so stupid I normally wouldn't do that but I wasn't thinking straight...

at the time.
Anyways I noticed Monday of this past week while I was wiping I had brown discharge, which sometimes happens before my period but I usually get other signs such as bloating or really bad cramps letting me know I'm about to get it. The brown discharge lasted until the next day I had one strange cramp feeling in my lower abdominal. Then the next woke up I felt nauseated. The brown discharge came back yesterday but went away again today. I felt a bit sick earlier like my stomach hurt like it usually does when I have my period though. Tonight I feel extra tired! I'm really trying to pay close attention to anything different from normal. I was so paranoid I took a pregnancy test last night but it was negative. I know I'm still only a couple days off before my missed period, but why the brown discharge come go? Could I be pregnant?

I dont know why it comes and goes,but you could be pregnant If you are,Congratulations

you could either be pregnant or it could just be your period
I read somewhere that when there isnt enough oxygen down there
the blood can turn brown so wait a week and try another test
or get help (I know sucky option)