What Causes Spotting With Cervical Mucus?

Hi, may I answer your health queries right now ? Please type your query here...i have a 28 day cycle and period lasts about 4/5 days i turned up on 7th came off 11th my most fertile time was the 21st i had sex during this time and had sex on the 30th when went to loo was spots of blood in with cervical mucus (never happened before) only lasted bout 2 hours today 31st got slight cramping but not period like is there a chance the spotting was implantation?