Losing money of cause is a big thing.
"of cause" is not correct. Do you mean "of course"?
Losing money is, of course, a big thing.
I work for it day and night every single day.
"day and night every single day" sounds excessive because of the use of "single". It adds a certain emphasis to the statement. A more common or natural way of saying this would be "I work for it 24/7" where 24/7 refers to 24 hours per day, 7 days per week. This is a saying though, so I'm not sure if every English speaking dialect would understand.
You could also say it as "I work for it every day, day and night."
But more than that is the psychological trauma which I've been through, it's like having a black cloud hanging over my head.
This sounds natural.