Compare values of two dimensions (same column)

i've been working on a inventory report where i have to compare the previous month value to current

problem is: the excel report is a pain

We are currently working on this same report on Power BI.

Today we have:

While trying to do the same at Power BI, I couldn't manage to reproduce the DIF(difference) column, as follows:

TL;DR: I need to create a column where i can do "FEVEREIRO" - "JANEIRO"

Here's an example of how this table is set:

Thanks in Advance!