>   I've also noticed that all fruits make my
>> tongue burn.  Anyone have a clue on that one?


You are experiencing an instinctive stop that means that your body
metabolism can't use them advantageously at that precise moment.

differents reasons i can see!

-- the fruits are unripe
-- they are eaten at a wrong time ( after other foods ? try to eat them in
an empty hungry stomach)!)
-- the fruit chosen is the wrong one at that time ( choose by smell , take
the best smelling which makes you salivate) not all fruits are equal in what
they can bring to your metabolism!
--You have a temporary need to not eat fruit.( wait for an instinctive
appeal to them , smell them from time to time)

In either of the cases ,take this information ( given by your senses) as
relevant only to the moment the fruit is tried. Don't make a definitive
statement like < oranges are not good for me >
in accordance with you metabolic state,  the taste of an undenatured food
 raw,  unprocesssed , whole) is an ever changing experience.
enjoy or reject !
jean-claude