For me it is the fact that our blood contains iron. I earlier used to believe the word stood for some ‘organic element’ since I couldn’t accept we had metal flowing through our supposed carbon-based bodies, till I realized that is where the taste and smell of blood comes from.
A lot of music generates unpleasant sensations for me too, though I can tolerate it a bit. Unlike the other commenter though, I can enjoy a lot of other music. What’s unusual in my opinion is that it’s all music, not the negative response. Lucky you if the worst that music can get from you is indifference!