Getting Plenty of Fresh Air - good for house or not???

[Guest guest]

I thought having lots of fresh air through my house would be good. I

put a fresh air intake in which helped immensely and there is a Merv

11 filter on that that I changed frequently. Since that was so

helpful, wanted more and I decided to open my windows as much as

weather would allow. I've been doing this for months. The mild

winter allowed it. Now it is turning warmer and more humid and I

think my house is smelling musty all over. It was only musty in one

bedroom before and I was going to investigate and some times in the

basement. Now it's the whole house. Did I do the wrong thing by

throwing the windows open so much?? The other possibility is my nose

is becoming more sensitive. I hope it is that is the case but I

probably shouldn't count on it.