Thanks for your query
main causes of having a constant sweet taste in the mouth are:
1. Indigestion: Individuals who suffer from digestion problems and who suffer from GERD( Reflux) might experience this problem. In some conditions, the acids in the stomach travel upwards and reach the mouth again. This is the reason the individual might have a sweet taste.
infections: This is the infection which might be caused by pseudomonas, a bacteria.
3.Neurological disorders: This might be caused when the nerves of the nervous system do not function perfectly and do not send and receive the right signals to and from the brain.
I think you should take some antacids Like PPI's, H2 antagonists. If that doesn't we have to go in for some tests.