It's cold and dark outside now in Sweden. What is the temperature in your house? Are you giving the plant any extra light?
As Cym Ladye wrote, cold and wet will rot new growths. It is also possible a snail was in the soil with your plant and ate the base of the plant, allowing infection to enter.
Cymbidiums can be difficult to grow in cold-winter climates. They take up a lot of room. They need very bright light when growing, so many people use artificial lighting in the winter. They like to be cooler than many people keep their house in the winter.
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