Lower left abdominal dull pain when i walk. lymph also swollen that side. & i'm gassy. doc said possible infection or hernia, most likely infection?

Difficult to say: I think you need some vital signs and a good physical exam. If the doc doesn't know if you have a hernia or lymph node, see another doctor. If the pain gets worse I would be concerned for diverticulitis and that means you need to see a doc ASAP as you can have an infection in your colon which can potentially rupture. This is speculation as there is limited information. Either way, get a good doc.