weird cycle :/? help!

Danielle

I wanted to ask you girls for some help! Today I started to experience some light period aches followed by a mixture of what looks like old and new blood of which some is quite stringy (sorry for tmi), with a dark brown clot lump, no bigger than a 5p ,Does this sound like it could be an implantation bleed?? I am still experiencing this but it's slowing up, My cycle is usually 29 days so very early for a period. I don't now when I ovulated... however glow says my fertile week has just passed last AF was quite light.. and last time we DTD was day before last AF came x HELP! 
I'm on CD 18 today