Fifths disease

My wife and I were around a child that has fifths disease, we went to our Dr. and she had a blood test for parvovirus B19.  The initial results were good, with high IGG and IGM numbers.  We then went for another blood test a few weeks later and the results changed, with the IGM numbers going from 3.3 to 1.1.  This was a cause for concern for our Dr.  Does anyone know what these numbers mean?  We now have to go for a consult with a specialist and have to do a level 2 ultrasound.  No one will tell us why we have to do all of this now.  We just want to know what the numbers mean.  Thanks

[feather2e]

Not sure if this helps but it is what I could find.
http://www.cdc.gov/ncidod/dvrd/revb/respiratory/B19&preg.htm
http://www.cdc.gov/ncidod/dvrd/revb/additionalinfo.htm