Could A Small, Painless Lump On My Mastoid Bone With No Redness Or Symptoms Still Be Something To Worry About?

Hiya, mastoid bone seems to have a little lump on, had a health care professional check it when was having a dressing for something unrelated changed on Sunday and she said was just mastoid bone and may have a spot under skin or something. No redness, not sore, no other symptoms....? Worried I should be getting a second opinion though!