But then when i try to pinpoint where the pain is coming from it seems to still be in my armpit and not my heart. I would imagine its the lymph nodes reacting to a situation in the body.
Lactose intolerance can manifest in many strange ways.
Mine was a knot in my solar plexus. I've spoken with other ppl throughout the years that had other reactions. This sounds like a chemical pleurisy and is an early warning from your bodymind that you are getting close to some limit. Listen to GeneAum. This WILL probably go away by itself.