Possible for an enlarged deep cervical lymph node to grow over 6 months due to mono? or unlikely to cause enlarged (and slightly growing) that long?

See your PCP: Lymph nodes can get enlarged for a few reasons, and some of which are benign and possibly a result of an infection. Enlarged neck nodes do however need to be properly examined in addition to any other symptoms like night sweats, fevers, and weight loss. This requires a proper workup by your primary care provider. I recommend you make an appointment as soon as possible.