It means you have an extreme case of some affliction, ranging from being lovestruck to having a cold.

Literally means someone is having a bad time, not lucky or just something bad is going on around them. It can mean many things depending on the context but it's used mostly in negative situations.

Actually, I dont think that it is always negative. When in my younger days and my buddues would make comments about my addiction to my 1st girl friend, they would say it to me. You got it bad. So, I would agree that it mostly refers to an addiction, compulsion, etc. Not always negative.

In simple form, it means "you have bad luck."