Can stomach flu be treated at home, or is medical treatment necessary?

Thank you for your question. I would need to understand your symptom better as the throat is a symmetrical structure and moves symmetrically (right and left sides) on swallowing. Since you mentioned that you have a "flu" a few weeks back and it appears to be coming back, there is a possibility that you may be feeling the mucous from the back of your nose flowing down the back of your throat (maybe more on the right side), hence giving you the feeling that your throat is "moving to the right".

Both gastric flu can and food poisoning may present with similar symptoms and difficult to differentiate although the former tends to present more with fever, nausea and vomiting while the latter is associated with ingestion of contaminated food that cause cramps and diarrhoea most times. As far as treatment is concerned, adequate hydration is the most important aspect besides controlling symptoms. In some cases, a course of antibiotics may be required for suspected bacteria infection especially if the fever is associated with blood stain stools.