Welcome to healthcare Magic!
The bitter taste in mouth is the symptom due to many drugs including bactrim
which is a sulfa
drug and also the prednisolone
The alteration of taste is never permanent and will resolve after 3-4 days of stopping the drug.
The sweet taste you are feeling is probably the overshoot of feeling the normal as sweet because the bitter is getting resolve.
you will very soon get adjusted to the normalcy.
I hope the advise would be informative and useful for you.