Can Brown Discharge Indicate Pregnancy Despite Negative Pregnancy Test Results?

Hey! I had sex like two months ago. It was my first time. He used condom and changed it when needed. Then I m doubtful in this case because he inserted his fingers inside my vagina which may have sperm on them. I took ipill the second day (within 72 hours). Then few days later, I got brown discharge. I haven t seen any red (normal colour of mensuration blood) since then. Since, I was so frightened, I took pregnancy test 4 times and all came negative. But while browsing internet, I came across some confessions which blew my mind and I m frightened again. Please help me. What should I do? Also, these days I m getting tired very soon in performing my daily activities.