Help?!!

Af was 3 days late and I've been having some very mild cramping. I never have cramping with AF. I've since had 3 days of light, brownish pink blood, again unusual as flow is normally pretty red and heavy. Today I notice a couple clots (or what I think to be clots) and bleeding stopped. I have an appointment tomorrow but trying to ease my mind. Not possible to be implantation bleeding, right? Either way something doesn't feel right and I'm super nervous for some reason. Any advice would be helpful. Thanks!