Hi I have tenderness and discomfort in my left armpit. My GP did a limited auxiliary armpit ultrasound and the lymph nodes seem the same size as my armpit. I was then given antibiotic - clindamycin - 300 mg for 7 days. This is my third antibiotic in 6 months and I did not want to take it - should I be taking it or go for a more extensive study. I have had a cyst in my left breast very close to the site of the discomfort, but because my last ultrasound was a year ago, the GP did not feel he should scan the breast as well... My chiropractor said it could be a pulled muscle, because the pain started after I slept on my left side for an entire night Is there a way to rule out muscle from other possible pain?