Any idea why get headache after 1 sip of coffee (hot or cold, black) decaf ok and tea and soda ok?

Caffeine: Regular coffee has a lot more caffeine in it than decaf coffee, tea, or soda- so I would wonder if you are very sensitive to caffeine and it causes you to have headaches at the higher concentrations. If you know it affects you that way I would advise you just avoid the higher caffeine concentrations altogether.

Caffeine: Caffeine one of the active ingredients in coffee and can be used to treat some headaches like migraines and can cause headaches especially if you regularly drink coffee and then stop. One sip would not typically cause headaches. In addition if you have no problem with tea, chocolate and caffeinated beverages it is unlikely to be related to caffeine. Perhaps it is the brand or some additive?