What Causes Vertigo At Night And Feeling Of Water Accumulation In Ears?

Hi I had back surgery 4 weeks ago. A week after the surgery it felt like I had water in my ears. Soon after that I experienced Vertigo at night when I turn from the one side to the other side. And I felt a little dizzy an of balance diring the day. I slept with a oily cotton wool in my ears last night. This morning when I took it out, there was dry blood on it and when I cleaned it, fresh blood was on the tip of the ear bud. What could this be ?