I've had this cactus for about 6 months, and I can't figure out how to make him happy. I've tried watering more (he especially didn't like that) and I've tried watering less (better, but still not good). The first picture shows him when I first got him, he's the one in the red pot, second from the left. The second image is him now, much less healthy but not dead. Please help me identify him so I can learn what he needs and take better care of him!
