Google Serp Dancing

One of my myspace site ranked #2 on secondary major keyword and ranked page5 on major keyword.  Then my site was dissappeared from SERP on major keyword(myspace layouts)  and pushed down to pg3 on secondary keyword about 10 days ago.  This morning, I checked it again, site is there..yeah..last 10 days my traffic downs about 30-40%.  I was very fraustrated because I can do anything about it and all I could do is wait and wish luck.  Wondering why this happening.  Anyway, today I am happy.  It is happy chinese new year for me.