This is the most debilitating symptom in my illness.
I too have a big problem speaking, more so to strangers because that takes a lot of effort and concentration. Trying to appear normal in a brainfogged, drunk state takes too much of me.
I get this flu-ish feeling in minutes when talking to someone or doing something that requires concentration. If i don't stop right then and there it develops into shakes, reddened eyes, high heartrate, pale skin and a crushing headache. Then i can feel the aftermath for days because of a hyperactivated CNS.
Yesterday we had a new maid come by to clean up, i speak a bit of her language but it takes a lot of effort to communicate, she doesn't speak my native language or English, maybe just a few words. I felt flu-ish within 2 minutes talking to her and today is even worse. I can feel the inflammation in my veins and it drives me nuts. My speech is incoherent and writing is difficult as i fail to understand which word goes where in a sentence.
My deepest sympathy to all of you who suffer from the debilitating symptom of being unable to talk.