I have a 4 year old male Shih Tzu. He has been pooping in the same location for the past two days. And that location is inside of our house. We have never had a problem with this and we haven't moved recently. I was recently sick, and he stayed with me a lot of the time. The stools are loose to hard. Any ideas WHY he is doing this?

Shih Tzus are notorious for being dirty in the house, mine was terrible, I never got her fully toilet trained before she was re-homed (long story)

Dogs know when people are sick as well, it may have something to do with that. I know mine barely leave my side if I'm sick in bed, he may just not want to leave you to go outside.

Then the third factor is his health, there are a lot of things that can cause loose stools from worms to stress to food, only way to know there is to get him checked out by a vet.
In the meantime though you can try adding a little canned pumpkin to his food and perhaps switching to a diet of boiled chicken and rice until he is back to normal.