I'm hoping someone can help me but I'm afraid it's too late. I've had a cactus for about 3 years and he suddenly started losing color, turning brown, and getting a little droopy (see pictures) a few weeks ago.
I moved to a new apartment 1.5 years ago, where I put the cactus at a northern facing window. It was doing ok there and I watered it the same amount as my other cacti, which is once every few weeks. I also have him in a pot with a hole at the bottom and use a cactus mix as the potting medium. My other cacti are doing perfectly fine.
Then a few weeks ago I noticed this one was starting to lose its dark green color, which led me to believe it wasn't getting enough sunlight. So I moved it to another space where it could get more direct sunlight in the mornings, which happened to be next to an open window. After I moved it, it started to get noticeably worse- looking a bit 'shriveled' and turning brown at the bottom! The brown part is not mushy, although I can tell the cactus seems a bit weak because part of it is starting to wilt. I really don't think it can be root rot because I don't water it enough for that to happen.
Any ideas what's wrong with it and if I can still save it? Thanks!!