I'm not on cytomel anymore, I take a different type of med (tried way to many).
But, the reason I'm replying is it looks like you have only had T3 for 4 days..........?
4 days is not nearly enough time. Some people even feel somewhat worse the first 1 or 2 weeks when starting any type of T3 med. You usually feel a little hot, sweaty any nervous as the body gets used to it.
If your nerve and muscle issues are from lack of T3, it will take 2 weeks to a month minimum before you feel the positive effects it can give you. After that, T3 can slowly heal the body taking up to a year. Ive been on one brand of T3 (dessicated actually) for almost a year now and my body slowly feels better every month. I douldt it will all go away, but I can do things again without pain, bike, ski, snowshoe, lift. The pain that remains, I have to manage.
Some of the nerve and muscle issues can be from what Barb mentioned, as well as lack of Magnessium (any type but mag oxide works). So you need to try these things at some point. If you try everything at once, you wont know what worked and what did not.
Patience, but none of us like the thyroid waiting game!
I don't recall if you had your vitamin B12 tested. Low B12 levels will cause the numbness, tingling, etc. I have permanent damage due to untreated pernicious anemia.
Also get your vitamin D tested, if you haven't.
My problems are this : weakness in the legs, numbness and tingling in the hands,arms, and legs, terrible low back pain......they started last Fall. I got dry eyes out of nowhere 2 years ago... I want the weakness in the legs, the numbness and the tingling, and the low back pain to go away - so far in 4 days, NOTHING. Should ANYTHING be DIFFERENT by NOW ???
I've been on both synthroid and levo (currently on Tirosint) and both cytomel and generic T3 (currently on generic) for over 2 yrs; yes, it "did the trick", but I have never been completely "symptom free"......... there are always those little nagging aches/pains, etc - at least for me - that I really no longer attribute to thyroid.
Contrary to what we often see/read, I did not feel an immediate improvement when I started taking cytomel. It took a while (several days) before I felt much difference, in regards to symptoms, and it took quite a few months before my FT3 actually came up much.