I today found a lump under my armpit which i thought was a spot i put pressure on this and it moved should i be concerned?

Likely lymph node: This sounds like a lymph node or "gland". Lymph nodes store site cells which attack infections. Usually when there is an infection nearby, it is tender. Another cause of a swollen lymph node which concerns everyone is cancer, either in the node itself or for you is actually a breast lump. I would see an MD to confirm the diagnosis.

Yes, if it persists: The most common cause is an infection or a blockage in a gland (hidradenitis). This can be caused or aggravated by shaving the area. If it persists more than a few days, see your physician for treatment.