Pregnant with bleeding

Found out I was 2-3 weeks pregnant, a day later I was spotting now it is like a very light period, but with a dark red ish brown blood. It comes and goes sooo I think it's still spotting... but it's been 2 days and I'm kind of worried. I have an appt. Tomorrow but I just want to know opinion. Does anyone know what it may be or what I should do? I am super tired and my bobs hurt... and I have this spotting/ extremely light period...