Cumulative difference in power BI on calculated measure.

Hello Team,

I want to calculate cumulative difference current minus previous based on date. but the date value is not fixed for minimum number of days it can be any date when the refresh is ran.

based on these refresh dates i need to calculate cumulative difference 

I ahve written my doubts in red what i want to calculate. and have done this calculation in excel formula but same i want to replicate on power bi. I ahve searched all but there are many complications. i ahve written step by step what i am doing and what i am looking for. Please help me. I am not able to attach the excel so i ahve attcahed the screesnhot of adta with my calculation done based on which I want other calculations. once you reply if needed share your email id so that i can mail you the excel if the image is not clear. My email id is [email protected]please check this