I have been experiencing pain in my upper left abdomen for the past eight hours. The pain intensifies when I press on the affected area and also worsens when I walk. Doctor, could you help me understand what might be causing this pain in my upper left abdomen?

Recently, I often burp, have a burning sensation in my stomach, cough and have a sore throat in the morning, as well as pain on both sides of my chest radiating to my back. I feel choked after eating, have a headache, and slight pain in my back. Eventually, I found a palpable swollen lymph node in my neck, which is mobile, soft, and slightly painful. I wonder whether choking and swollen lymph nodes in the neck are signs of gastric reflux.