Period pain or not...confused!

I am meant to start my period this Wednesday. However I got what I thought was my period... Last Thursday... But it was less than a ten pence piece worth of blood on my towel.. The next day I got mucus and light pink blood. Nothing Saturday, nothing Sunday, tiny amount on pink blood on toilet roll last night... Nothing since then.
My periods are never early, they are always heavy and always last 7 days.
Now I have pain in the left side of my ovary area... And extreme pressure between my legs. 
Negative pregnancy test too. I've previously ended up in hospital with this pain and they never got to the bottom of it... Has anyone ever had this... Does anyone know what this may be...