For the past 1.5 months, I've had a dull pain on the left side of my chest almost strictly when I burp. I have no other symptoms other than the presence of a swollen, tender infraclavicular lymph node that appeared around the time that I first noticed the chest pain. The lymph node has since decreased in size substantially and is no longer tender. I am a 31 year old male, I run five days a week, and have no other health issues.