Sometimes it feels like there is water in my lungs but it happens randomly and i can breath the same. it just feels weird and i don't know what it is.

I'm not exactly sure: what sensation you are describing. Of course there are serious problems that cause actual fluid build up in the lungs, which can be diagnosed by physical exam or x-ray, such as pneumonia, heart failure, etc. But most of these would also cause shortness of breath/coughing, etc. You may have a patch of inflammation which sounds/feels like rattling. It is worth a visit to your Doctor for evaluation.