my daughter has been called back for another blood test to check her full blood count.she only had the first one 6 days ago.the other tests included thyroid,u's & e's,glucose & esr.all of these came back ok except her full blood count.why has she got to have another so soon. 13 year old girl.reasons for tests,headaches,tiredness,dizziness,generally feeling unwell.started periods 3 years ago