What Causes Sweating With Extreme Odour?

I am a 40 year old male. In the past year (on my head only around my ears mostly) when I sweat it smells exactly like vomit. It is annoying and embarrasing. I have an arachnoid cyst in my brain, but I am told it is not that, but more a cleansing attempt by my body. I take the same protein and supplements for years. What could it be? Help!