My Period Is 2 And A Half Weeks Late. I

My period is 2 and a half weeks late. I have been feeling very nauseous lately, my breasts have been tender, and i have been very moody. I started to think that I might be pregnant, so I took 5 pregnancy tests but they all came back negative? I am very confused about this. Then a couple days ago, I got a very disgusting smelly brown discharge and it went away after about a day and a half later. Then my fiance and I had sex today and it came back for about an hour. Any thoughts?