From the symptoms it can be a swollen lymph node, sebaceous cyst or a boil. Lymphadenopathy (swollen lymph nodes) is usually caused by a viral or bacterial infection. Other causes include allergic reactions, arthritis, cancer, metabolic diseases, and an overactive thyroid (hyperthyroidism).
Please get an evaluation done from a dermatologist and get it evaluated. Till that time, apply warm compresses and some topical antiseptics and antibiotic cream.
I hope it helps. Take care and regards.