眩晕means physical feeling,like someone see blood may feel 眩晕，and it more like written language.晕乎乎，we don't use it.晕晕乎乎 like:I don't sleep at all lastnight,so I feel 晕晕乎乎，or I have a colleague working slowly and always wrong.we always say"她整天都晕晕乎乎的“晕头we don't use it a lot,someone does something wrong,we may say"你晕头了吧”。

we do use "晕乎乎"，the meaning is the same with "晕晕乎乎",just a little difference in the usage ---------"我觉得晕乎乎的"，“我觉得晕晕乎乎”."晕晕乎","晕晕乎乎"and"晕头"are used in oral Chinese. "晕头"are used when you think someone doing things disordered or unreasonable. It is a tone of unsatisfied. so don't say "你晕头了" to your boss,or you may be fired tomorrow ^ ^

Yes,They are same meaning , but sometimes 晕头 means that somebody was confused by something.