What you are describing certainly isn't typical of the onset of ALS. For all four of your limbs, your back and your jaw muscles to be affected all at the same time is very atypical; ALS most often sneaks-up on you. It sure sounds like a weird virus, or some type of metabolic problem or autoimmune problem or anxiety driven.
You got your EMG and it was clean. That is a very good sign. Tell your psychiatrist that your meds have made you worse and he/she will change them.
If you've been on this forum for any length of time, you know that Al is ALWAYS right. Listen to his advice and get on with your life and concentrate on feeling better.
Take care.