Cumulative value with conditions (or other solution)

Hello fellows! I have little experiencie with DAX. I've been trying to create an expression to solve my problem.

I have a 3 tables.

Initial Stock (not linked with DateTable, because it is a snapshot of my current stock position)

Transit (linked with DateTable)

Demand (linked as well)

Final_Stock ( Initial Stock + Transit - Demand)

Here is where I'm stucked, what I've been trying to accomplish.

I have the initial stock and did the measure to give me the Final Stock for this month (Initial Stock + Transit - Demand) .

However, for the calculation for the next months, the initial stock to be considered should be the final stock from previous month.

The biggest problem I'm facing: If the final stock from previous month is negative, the next month should considere 0 as the initial stock and start over the process again.

What I did and is not working well.

Cumulative Total =

      CALCULATE(Medidas[Final_Stock],

               FILTER(ALL('Date'),

               'Date'[Date] <= MAX('Date'[Date])

          )

)

 

I tried to create a conditional formula, but is not working correctly.

 

 

Any help will be appretiated!!!

Thank you all.