What Causes Prolonged Periods After Taking Plan B?

ok here it goes i have had a lot of fatigue in a last couple..did my blood test and found out my blood count was like 15 with that my inactive thoiroid of a little off now this is one part of it i had a ten day period after that i took plan b after a couple of hour i started spotting it went on for 5 day and then it stop this morning i started again ..is there anyting wrong with mr