A classic twisted problems caused by misunderstanding of how things work.
Oversimplification is the first thing we can see. Attributing kidney failure, anxiety, sleep disturbances, and overall well-being solely to the cessation of coffee drinking or drinking some legal substances that are rather well-researched is a little bit like masking everything with a smokescreen.
Working for 8, 12 or 16 hours on things without deeper meaning is the core reason of such problems. This is dark ages way of thinking. We're living in the age of informatics, but those systems are understood only by a certain part of society.
I would consider changing my life completely and start seeing a therapist who will help deal with basic errors in thinking.
Caffeine is a nootropic substance and it doesn't cause visible harm unless you're ingesting massive amounts without tolerance, like 1000 mg at once. Although it depends on a person.
It can make one feel uncomfortable if they suffer from mental health problems which is very common if one is fooling people with ads and copywriting for the living spending 10 hours a day on it. Or any amount of time and living in non-self-reflective way, but instinctive and egocentric.
Marketing and sales circles are very clannish and so, people will reinforce that belief that what they're doing is right because there is that clan that supports that belief. But it's just a group that performs a group rationalization.
All in all, one of the solutions is to change a job and start doing in life to DO Nothing and still be able to thrive.
I know 1000 excuses to not do so. But I am not life and it's not me that will give anyone cancer and a heart attack. And no, it's not caffeine giving heart attacks, but excessive stress, outdated ways of working and not understanding one's needs to heal themselves cause a doctor is only a helper and provides guidance if a patient is willing and open to accept help.
These are symptoms of "burnout" which in marketing and sales start after a few months of work. Free money, huh. You see how free it is.

If you can't do marketing / business without touching anything, simply don't do anything and think hard enough until you understand how to find real passion and work for fulfillment, greatness, not money. People go through homelesness, get kicked out multiple times until they learn how it works. You can't f*k with life, because it will not cooperate with you and it'll crush you taking you to grave.