My expewrience of SSRI's is that twitching is for most people, part of the SSRI experience. Its a result of the imbalance of other neurochemicals trying to compensate for having far too much serotonin in the system.
One aspect of it is known as Akasthesia, this is beyond twitching as it a constant squirming and restlessness which deprives the owner of it of any rest at all. A bit like being in some invisible torture instrument.
The other side of it is the sudden twitches - like little seizures and sudden but repeated cramps. Also "flashes" down the body, up the body, in the brain. Which cause twitching. When I was on it it also caused stuttering. I still stutter now.
You mess with the endocrine system and you then affect the nervous system (which is run on neurochemicals for its health and response and appropriate balance) at your peril. I did.
The nervous system then affects the muscular system.
Which can then affect the digestive system and so on. No one of the systems is divorced from the other, your systems work together, and try and compensate when one is not right or affected.
So rest assured, this is normal when on an SSRI which is a hugely powerful drug and is not fully understood yet.
I had to come off because it caused me to have a major seizure (which is why I have researched it now) the seizure broke my jaw and dislodged 3-5 teeth. Still cemented together to keep them in now, three years later. Hmmmmm !
cloudberry