Storage issue

[jv38]

I have an issue that I don't understand. I buy a case of wine per month for daily consumption, mostly for the week end. I store the wines in the guess room that is close and dark all the time with a temp around 70 degrees, set sideways and low on the floor.

Lately most of the wines that I opened have a funky smell. The smell is not overwhelming but is not normal for the wine, because I tried the wines before and they do not have that smell and are different wines, varietals, countries, still...

The only thing that I could think of that there is something wrong with the way that I storage my wines.

One thing that I noticed is that after a while, the smell goes out, but by them there is not too much wine left to enjoy...

What I'm doing wrong? I'm thinking about a wine fridge, only thing is that I don't know where to put it... (don't have space...)