Help!!! Lines are faint and I had brown/light pink discharge

Hello, this is my first pregnancy. I am 4 weeks 6 days pregnant. I took 2 pregnancy tests after my period was 3 and 5 days late and both were positive. Today when I went to the bathroom I had a light pink/light brown discharge. I was freaking out so I waited 20 min. and took another pregnancy test and it came back positive and the colored discharge was gone. Am I having a miscarriage? What’s going on? Help anyone? Also my lines are NOT getting darker, is that a bad thing?