Ren honestly wouldn't have been quite as affected by the whole ordeal if not for that spirit—he would have been able to move past the slow drain and the death, since they were over now. But the creature that took him left its mark in more than one way, and by this point it's probably obvious to Obi-Wan that his right arm is practically unusable.

He's determined to move past all of it, of course, but for now... he was having trouble. The most he could manage was an occasional numbness about it all.

"Whatever is in the pantry will do."

Ren could only afford to be so picky right now, and honestly, after a month of prison food, practically anything else was worth having.