Should I have my nipples checked out? Lumps developed under my nipples during puberty and never went away. I'm 18 and they still exist after 4 or 5 years. I am very self-conscious but should I be concerned?

Any . Any lumps in the breast warrant investigation. Since they are in both breasts (bilateral) then that is very reassuring that it is likely not malignant. Your doctor will need to examine your breasts, and based on his/her findings will either monitor you over time, or order an ultrasound and/or mammogram. Best of luck.