I have a lump under my arm pit?

It is likely a lymph node. Lymph nodes remove toxins from the body. If you have a lot of toxins they will swell up. Keep in mind, in many cases this is how cancer starts. You may want to look at your diet and environment to see if you can find anything that could be causing your toxin levels to be high. Many doctors mis diagnose this as cancer, but it can be corrected. Good luck with your appointment. I hope it is nothing serious.