Small hard lump deep within neck for two months. ultrasound results say "no visible mass. there is shadowing 5 mm calcification in the deep soft tissue of the left posterior neck, seems to correspond to a palpable lump". feeling scared about this?

Palpable lump?: If this has not gone away by now, and it's palpable, consideration may be made for excisional biopsy. Have it removed and sent to the lab. Most of the time these things are benign, but sometimes we just need to know for sure. That being said, calcified things are usually stable and chronic. You may want to discuss excision with your doctor.

Neck lump: Great that you had it checked. Did you have any sort of prior injury to that spot? Even acne can leave a calcification behind after it heals. Did the radiologist recommend repeating the sonogram in 6-12 months? Might help to see if there is a change over time. Don't worry, but do recheck it.