HELP Den. Love memory fit (den.white rabbit) and C.green emerald "orchid" queen

[Lorizb]

Please help i'm a beginner. My dendrobium started getting black and yellow at the tip, it started to spread below to the rest of the "stalk" (don't know the name). I thought it might have been from too much water since it's been raining here quite a bit, i put it under something that still allowed it to get light but that wouldn't allow as much water into the pot. it didn't stop spreading and i just it cut it off before it spread more, i dont know if that was the right thing to do. i dont know what the problem is or what caused it. on the green emerald, i repotted a couple months back and noticed that the roots were rotting, it outgrew the container that i bought it in. I cut some of the rotted and dead roots off to let it breathe, but there were so many of them it didn't leave it with much. the plant was actually doing very well for a while, i saw a lot of new green roots. lately it's not doing so well, the leaves are wrinkly and my orchids usually grow very fast, i did get a new leaf in and it is a big one in the back...but the wrinkles on the leaves are worrying me...i dont know if it's getting too much light or what all of my others are doing exceptional except these two. please help this is especially my favorite one. they both smell so beautiful. thank you.