Four months ago I found a hard lump in under my armpit and at first the doctor said it could just be a lymph node and to just wait a few weeks, still no change so I went back and an ultrasound was done. I was told it may just like like some kind of muscle, which just doesn’t make any sense to me. The doctor couldn’t explain it but just said keep watch of it. Should I ask for another test. It’s hard painless and non movable and has not minamised. It’s starting to cause worry for me?