Spotting

2 days ago I had a tinyyy bit of brown in my underwear in the morning. Yesterday morning I had a bit more brown discharge in my underwear. Today I had a bit more brown in my underwear. This only happens in the morning. I am cramping and period is due in 2 days. Does this sound like implantation bleeding to you? I tested today but it said negative. I have very normal periods and never spotted before. I had sex 4 times during my fertile period.