Burning Tongue and Geographic Tongue

Hi,

I'll start first of all by saying I have read EVERYTHING there is to read on line about Burning Tongue and Geographic Tongue and I know there doesn't seem to be one reason, or even a proper known reason for it.
I wanted to know if any one out there has this as well and what they've been told or found out maybe as to why they have it?
I have had this problem for over 6 months now, started as a metallic taste, then after 6 months it turned to a bitter taste and wasn't there all the time and now it's only there every now and then but is more of a burning, tingling sensation. I also had 2 ulcers during the beginning of this.
I am not menopausal, am not on any medication, it's not thrush, I'm not allergic to toothpastes or dental things and it's not food. I have checked all these. I am also not anaemic, diabetic or lacking vitamins.
My only other suspicion is my stomach, acid or the like.

Can anyone shed some light?