(Help) why yahoo linkdomian number is decreasing?

Hi

I am new here.I have a 3 months old site.I was building link by simple blog commenting.Last week i checked my yahoo linkdomain number are 376 and yahoo links are 145.

But suddenly day before yesterday i noticed that yahoo linkdomain number are 117 and yahoo links are 72.

And today now yahoo linkdomain number are 116.

It seams that the number are decreasing day by day.I am not understanding where is the problem.Any idea of anyone about the cause?

Note: I have hired a guy to build a link pyramid for this site and he started work from last week.Is a cause for decreasing my back links?

Thanks in advance