Last pic is from a week ago

I see a couple things wrong, the soil looks extremely dense, I always do a 50/50 mix, perlite & potting soil, I believe the soil was to wet and has started to rot the corm. I would gently take it out of its pot and check to see how mushy the corm is, if it's not mushy you can still save it by putting it back into the 6" pot with the amended soil, watch your watering, container grown like moist not wet soil.

I actually did this yesterday. Took it out, roots look fine. I couldn't find any perlite so I added some succulent soil mix in, maybe about 20%. I have not watered it since I repotted it, not sure if should? I also did not put it back on the 6in pot. Would you say that's necessary?

I hate to say it looks like it's at the point of no return. Being in a pot that size, indoors especially is the number one issue. I would not water it again. It is either going through corm rot now or stem rot.