Period due today

According to Glow, my period is due today. But I have brown spotting. But not very dark nor is it very faint. I'm wondering if it's implantation bleeding or really spotting before my period. Yesterday I wiped down there and got clear CM with a string of blood. Then it went to brown spotting. 1 time outta the 4 times it went on my underwear. The other 3 times is only when I wipe.