THe rule of thumb is for Fre T4 to be at or a bit above 50%. and Free T3 to be between 50% and 67% maybe leaning more towards the 67% moreso than towards 50%.
You are testing at:
FT4 50% of the range which is RIGHT on the mark.
FT3 68.4% of range Again just about right towards and slightly above the rule of thumb range.
So it is possible that a slight decrease MAY be in order. But not unless you have been dealing with this reaction and symptoms for awhile. How long have you been on your current dosage?
T4 medication takes up to 6 weeks to stabilize. So usually there is not a peak or surge of thyroid after you take a T4 only medication. Although I have read that it can. But that may be a result of what gimel stated above, and less about the T4.
Reactions like that when taking thyroid hormone have been reported as possibly due to low cortisol or low ferritin. So, It would be a good idea to get tested for both.