I took out my tampon and there was something on it..?

I've been on the pill for three months now and I take the sugar pills and i'm on my second sugar pill and got my period this morning. Its been really heavy and just before, i went to the toilet and took out my tampon which had been leaking all over the place, and as i was wrapping it up.. fyi this sounds really gross.. there was this little, like, chuck or piece, that almost looked like a small chunk of brain. i have no idea what it was but then i looked in the toilet and there was another bit in the toilet. i'm really freaked out what the hell is it! and the blood is really gooey and lumpy..