Sick sharry babies with yellowing bulbs! Please help!

[majormtn]

Hello everyone!

I purchased this orchid off of ebay some weeks ago and it keeps getting worse and worse.



The seller gave me a discount since I paid for an orchid with a flower spike, and the spike was limp and brown on arrival.

I really believed that after removing everything that turned yellowish/brown, the orchid would get better.

Unfortunately, I haven't been able to control it and it has spread to 3 of the 4 bulbs it had! I have no idea what it is and how to care for this orchid. At first, I thought it was some sort of rot, but I'm not sure.

Another bulb (not pictured) is turning yellow and has similar discoloration at the bottom.





I really want these guys to survive, but I fear that without the proper treatment, these bulbs aren't going to make it