I have a lump/knot on the left size of my neck, it does hurt be it's worrying me. i had blood work done about 3 weeks ago and everything was good. could this lump/knot be cancer?

Follow up with doc: If it doesn't get smaller and go away or continues getting bigger, especially if it is hard, firm, and immobile, it makes sense to think about biopsying it for your peace of mind. If you and your doctor decide to do this, a referral to an Otolaryngologist or Ears Nose and Throat surgeon would be a good idea. If you have had a recent viral infection or sore throat, that may be the cause.

Low chance: It could be but chances are small. In your age group, there are very few cancers that can present like this and probability is still small. It needs to be checked by a physician and a decision whether to biopsy it or not needs to be made.

Enlarged lymph node: Lymph nodes on both sides of the neck become enlarged in response to an infection in the head and neck region, especially in the mouth or throat (did you have a sore throat recently?). If that is the case, the lump should disappear in a few weeks. If it persists, check with your dr, who may recommend a biopsy for pathological dx