What Causes Constant Burning Sensation On Tongue And Lips?

I have a very strong burning sensation on my tongue. Seems like it's burning constantly. Even drinking water makes it react. My lips have felt like internal burning too. No matter what I put on them they burn and feel sensitive. I have looked at so many things that may cause this but no real idea. I have had issues with a root canal that has been retreated. It could be the antibacterial they use -nerve issues from chemcials on my tongue -allergies to something in my tooth. Could it be from too miuch fish oil in my daily veg/fruit drinks. Is it cayenne pepper ?

Went to gp for numerous blood tests yesterday. I cannot take much more. all food tastes terrible. I feel like I can taste my shampoo , soap

facial cleansers. it's gross. now it's getting a bit frightening. What kind of a doctor could help me? Thank you in advance