I wrote this reply in the other thread and I think it is relevant information to post here also:
It's because you have any possible fungal/parasitic infection. MCT is anti fungal, anti parasitic, anti microbial etc.
You are having a herxheimer reaction as a result of the MCT killing off/disturbing an existing infection of some pathogen.
These issues are complex but you should try and identify what the cause could be, and if that is not possible, either way you should proceed with a parasite cleanse/take antifungal measures.