Had a bad case of stomach flu. now neck is so stiff and sore and have shooting pain down right arm and can barely move it. is this serious?

ER or Urgent Care: I would advise an ER or Urgent Care evaluation ASAP. While your symptoms may be from a pinched nerve in the neck, there is a chance this could be from meningitis. If you had vomiting and diarrhea, this is likely stomach flu, and your vomiting strained the muscles in your neck - you still could benefit from medical care. If you have had vomiting only, go to the ER for further testing ASAP.