Thank you very much for your help. I was completely mistaken about the use of the correct verbal tense. However, I must say that I have just come across this example in Michael Swan's
Practical English Usage:
The shop's closed during the whole of August
So, following this example, we could probably say
: I was sick during the whole of my holidays. Well, if you insist, but don't blame me if you receive some strange looks.
Actually, it is not unusual to see "whole" in reference to months, years, decades etc., but your example for me is a "stretch". And if I ever meet Mr. Swan, I will suggest that he replace "during" with "for".