Hi, happy to help you on your health concern!
In the present case of solitary neck swelling or lump, if I were your consulting physician, I would just say you, 'nothing to worry!'
As per your description, it is benign harmless lesion like a
lymph node or a sebaceous cyst! The reason behind an enlarging lymph node could be head/neck/throat/ear infections,
tuberculosis or even malignancy! A sebaceous cyst, when infected, gets enlarged!
Take caution not to get injured there as this might invite infection.
If you are still worried, please go for an FNAC test for confirmation.
Hope you got your answer. Please feel free to write to us if any more queries.
Wishing you the best health!