Illness means a state of poor health. Illness is a more general term closer to sickness. It can refer to contractible pathogens (virus or bacteria) or just a lack of wellbeing. For example psychological problems which are often referred to as mental illness. If I am sick though I usually just say, I have a cold or I am sick or ill. Disease can also refer to contractible sickness, and is then it is an infectious disease. It can also just refer to when organs improperly function, such as heart disease or liver disease, which are most often caused by age and lifestyle. I would almost never say 'I have a disease' unless I was joking about how much I drink. (alcoholism is often referred to as a disease). I can't answer the swing question without more context...

One can be seriously diseased without being ill and without feeling bad as with asymptomatic cancer, and one can be seriously ill and feel bad without being diseased as with depression.

A little swing likely means 2 things. Just a swing that is small in size. (Swings being a chain suspended by chains or other strong material that keeps it held in the air) Or the slang sense. "To have a swing" means to have sex just for fun with someone who isn't your partner at any level. Think of meeting someone at a club, at work, ect. and having a swing with them without committing to anything serious. Kind of like a dinner date only with a lot more grinding and nudity. Also a higher chance of catching an STD. And now we've come full circle.

Okay, I got it! Thank you very much :) Also could you please tell me what SWING means if it doesnt bother you :(