What Type of repair do I need(is this a foundation issue?)

[Basit Siddiqi]

Hello everyone, 

I need help understanding the issue I have infront of me so I can reach out to the correct people to fix the issue.

I just visited my tenant over the weekend and she described to me the following issue.

There is a crack in the pavement outside of the the house on the floor.
The crack is currently being covered up so rain does not pour in.

However, it appears that water got through the crack in the past and flooring in the house is slightly raised. I know this because they are having a tough time closing and opening the backdoor. The raised floor in the back prevents it from opening and closing smoothly.

Is this a foundation issue?
if it is not a foundation issue - what kind of issue is it?
has anyone experienced this issue?
Should I be worried?

Thank you in advance for any and all answers.

Basit