Lymph nodes are small (1-2cm) and bean-shaped nodes. they are very important to your body keeping you healthy. 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).
In sinusitis, the glands in the neck are most likely to swell—a common response to a cold or upper respiratory infection.So pls don’t worry as it seems like it is due to your sinus infection,Treatment is usually cold compresses,over the counter anti-inflammatory analgesics(pain killers) like acetaminophen or ibuprofen,antibiotics if cause of infection is suspected to be a bacteria and surgical drainage if there is any abscess formation.
Hope it helps.Take care and pls do keep me posted on how you are doing or if you have any additional doubts.