I’m a 18yr old female never been pregnant or is pregnant I noticed about 4-5 months ago a white lump on my nipple I’ve tried warming it but it doesn’t do anything it never goes away and my boob is like constant pain but it feels just like growing pains I’m nervous and can’t find anything online about it pictures that look like it it says that that picture is matstits and it hasn’t gotten bigger but if you move it around like the lump comes out. Tiny bit and I can tell like under the skin it must me bigger I don’t see any noticeable bulbs outside of the boob. What do I do ? What is this ?