I work in an office and I usually sit down doing paper work. I work as a bookkeeper, my work is both standing and sitting depends on your department. I am the only one here in bookkeeping; other locations of the same company have chairs for their bookkeepers. I had a chair for 5 years, but my manager took it away saying it is not a sitting job. What can I do to get the chair back in the office?
You should talk to your boss, explain your situation, ask for the reason of the chair being taken and politely request your chair back.
When you request the chair be sure to explain that it helps with the pain, and focus on the part of not being a problem to develop your current activities.
Your boss is either a prankster, an idiot or devious.
If you have a medical condition, it may make it easy to force the chair back.
If he is being difficult, you can explain, that bookkeeping is actually done a lot sitting, nowadays in front of the computer.
The following link rates bookkeeping on 124 with 83.7% sitting.
Now he could have ulterior motives, maybe he wants to drive you out of employment or harasses you with this chair thing in some weird way.
Besides, I'm pretty sure unions and guilds have a thing or two to say about the idea of not providing chairs for employees.
So maybe find some literature on that in your locale to help you make the case next time you talk to him about getting the chair back.
Should he insist or maybe you come to like the idea of standing (which seems to have advantages) here is some info on desks and postures: