Ok, because mine has black spots that were spreading fast, and the general color has gone a bit lighter green. I was ready to chop as i thought it had a fungal infection but the flesh is actually fine, so i thought maybe it is thirsty ?
With succulents they need to be watered from the drainage hole, just put it in a bowl full of water for a few minutes and it will take what it needs and leaves the rest. You never want any water to get on the cactus they have little to no defense from mold.