Maybe brush your teeth before cleaning your ass out with the toothbrush
Every time you brush your teeth you get a headache...?
Okay, I see the problem... try this: instead of holding the toothbrush steady and shaking your head rapidly, maybe hold your head still and move the toothbrush.
Seriously though, no bodybuilder should be using tea tree oil extracts (especially not ingesting them) as they are estrogen active. Even products as benign as tea tree oil shower gel have been linked to markedly increased rates of gyno in teenage boys.
The Luke