You're slurring your words + your other symptoms: you should see a neurologist in order to have a complete neuro exam and rule out any neurological condition.
Please post your lab results from prior testing, along with reference ranges, so that members can assess.
When did you last have your T3 and FT3 levels done?
Your increased symptoms could simply be due to your levels being out of whack. Until my endo placed me on dual medications, T4 and T3 replacement, I, too, felt like a wreck. No energy, depressed, memory issues, excessive cotton mouth, muscle cramps, aches, pains, etc.
Found out my body somehow adjusted to the T4 hormone replacement med, and the T4 was no longer changing over to T3. He added Cytomel (T3 replacement hormone) to my synthroid, and I no longer have any of the horrible symptoms I was having....he's had to adjust my T3 replacement hormone once thus far, by increasing it due to the effects wearing off by around noon each day.
I still wake up with severe muscle pains, aches, and muscle cramping, but within an hour of taking both the Synthroid and Cytomel, everything is back to normal. My memory, speech, energy levels, etc. have all gotten so much better.
Just a thought.