Implantation bleeding or something else?

Hey guys, yesterday I started spotting at work. There were a lot of really small red dots, most likely clots. It freaked me out a bit but I just figured it was time for my period. Turns out I was 12 days early. My spotting got heavy enough to use tampons and the blood has been pink, dark pink and brown. However, tonight I used the bathroom and when I stood up I saw tiny chunks that almost looked like chicken fat chunks in the toilet. It scared me. They were light pink and dark pink. Just a few chunks. No bigger than a finger nail. Any ideas to what this is? Should I call my doctor?