Can fennel seeds burn your mouth and tongue or is it the turmeric in my tea? I think it's fennel, they are natural cultural remedy for gasey stomach.

Foeniculum vulgare. Precautions /risks when taking fennel (foeniculum vulgare): avoid in pregnancy or small children; avoid if allergic or known celery allergy; check sugar content if diabetic. Folk uses: dyspepsia, fullness, flatulence, stimulates GI motility or antispasmodic in high doses; secretolytic action in respiratory tract. It is always best to see your doctor however rather than self medicate ; suffer.
Fennel seeds. I think it is likely the turmeric in the tea that is causing you the problems. Try eliminating the turmeric and see how it goes. Good luck.