I Have Just Been Put On Efexor-XR 150mg After Having

I have just been put on Efexor-XR 150mg after having severe side effects from being on Mirtazapine for 6 months. I had previously been on Efexor for a number of years with little or no side effects. After 1 tablet I am experiencing vomiting, severe tirednesst inability t0 sleep, chest pains, pins & needles in left arm, headaches, nausea. Could these symptoms be from just 1 tablet of Efexor? or could it be a virus toptally unrelated?