So I'm creating this topic in hopes that when or if someone sees this they really understand that you really do need to take ferrets to the Vet at the slightest inkling that something is wrong. Everywhere you read online they list what can be wrong and that you should go to the vet immediately. Do this. I had three ferrets, I am now down to two. I may lose another in the coming weeks. I'm hoping I won't.

Oreo, male bandit, started to stop running around was only sleeping, hardly eating or drinking. He had only just turned two with us. I thought he may have the flu so I thought to give it a day or two to see. The days pass and he hasn't improved and I notice his heart beating seriously hard and fast. Okay, definitely time to go to the vet. Hoping for the best we brought him in, weren't told good news, had an x-ray done, and were told the terrible news. He had liquid filling his chest, compressing his lungs and heart, making it harder to breathe and harder on his heart. We had to put him down. Cancer.
First loss EVER.
Fast forward to now, hesitated again on our Momo, cinnamon female, hoping her Predisone could help, it seemed to until we stopped. We ended up bringing her in and were told her chest was filled with liquid, they removed some and told us to give her a medicine and make sure she rests. She now seems to be doing better, medicine twice a day, waiting on the results of the liquid to see if it's cancer as well.

If you ever feel or think you should bring them in to the vet, do it and never lose hope. They need you at every step. <3