When do you know it's time to stop working?

I like my job. But it's customer-oriented, and my cog issues have been getting very noticable and has caused a few problems for our office.

My boss has been awesome about providing accomedation for me. She doesn't fall under ADA since there's less than 15. She even went with me dropping to part time and hiring someone to fill in the remaining hours.

A part of me wants to stick it out to see if stuff calms down. Another part of me is worried since the MS hasn't calmed down for two years.

I have to admit I'm scared that I'm even thinking of leaving the workforce, but I'm not sure if this is the right time or not. I guess I'm just confused on where to go from here.