I have alump in myneck by my thyroid, severly vit d def. and calc. 10.4 - how likely is this to be cancer? taking high doses ofvitd-should i stop?

The real question: It's not "how likely", it's "does this need to be biopsied?" unless it's clear to your physician that this is just a common lymph node or it's been thee for a while and is known to be stable, get it sampled. All the rest, including the vitamin d stuff (probably from diet / lack of sunlight -- it's common today) is immaterial.

Re-check D when time: Patients being treated specifically for vitamin d deficiency require a repeat 25ohd measurement approximately three to four months after initiating therapy. The dose of vitamin d may require further adjustment and additional measurements of 25ohd.