Hello, I would be interested in seeing this rash. You may have developed any number of reactions to something you ingested (food/beverage), chemical exposure by inhalation or direct contact from your job or at home if you were involved in a painting project, etc. And the severe headache was part of the allergic syndrome or immune response your body launched against the entities or entities you were exposed to is the best explanation I can forward for your consideration. The fever was also part of the inflammatory reaction and resulted from chemical interactions causing the temperature centres of the brain to elevate core temperature at the instruction of the immune system in the event some foreign protein was responsible for the initial contact. Finding the smoking gun won t be easy since it appears you turned the corner rather quickly. However, some lab work and urine testing could reveal more details about the inflammatory reaction and a tox screen in blood and urine could reveal substances of interest that may have initiated the entire process. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr Dariush Saghafi, Neurologist