i'd ask your PT for help. mine gave me good ideas.
where is your pain from sitting?

some things that have helped me--
- sitting on the inflated PT ball with spine erect for working. sitting in motion as opposed to stagnant.
- reclining but trading off reclining with laying flat or standing. reclining in a chair that supports weight of head and back. but getting up frequently
- using a V shaped pillow to support arms. this can be gotten at a back support store. put the point of the V infront of you.
-putting some sort of support between shoulder blades if sitting against a chair or recliner back or even when lying down if nec. rolled up towel or long pillow or rolled up bubble wrap 6" long and diameter about 1.5". find what works for you. experiment
- a really good ergonomic chair -- one that fits you

- putting a pillow or something to rest arm/s on while driving. hold steering wheel near the bottom.possbly using a neck support in car if needed. again, ask PT. a good one will sit in the car with you to find solutions.