Data Lookup for Last 4 Weeks

I'm currently trying to figure out a way that will allow me to compare data from the last week vs the last 4 weeks prior. It also has to be possible to choose an older week and look at the four weeks prior to that date as well.

I have created a dummy version of how I would (ideally) want it to appear with some dummy data but I have no idea how to be able to do it - I'm not able to use Pivot tables in this instance.

Data Lookup Question.xlsx