Small 1 cm lump where neck meets shoulder, firat noticed over a month ago. painless, underskin down toward the muscle. is 14 years old.

See your doctor: This could represent a swollen lymph node if it's closer to the neck. However, given that it's 1 cm and persists, this should be evaluated in person by a doctor. It might require x-ray imaging or even biopsy to ensure that it's benign and not representative of some kind of malignancy. Don't panic, just be cautious and have it evaluated soon.