Not likely. The area below your right earlobe is more likely to have a lymph node. The thyroid is more toward the center of the front of the neck.
Lymph node. Likely a lymph node (as dr. Majeroni noted). Lymph nodes can be enlarged from infection (eg, inner ear, throat, etc). If it is increasing in size or persistently enlarged it should be investigated. Some lymph nodes may persist. Another cause of enlarged lymph nodes can be cancers such as lymphoma or other cancers.
Not thyroid cancer. It could be a small lump in your parotid gland (saliva gland) it could even be part of the vertebrae that make up your spine. If you are concerned about it I suggest you see a doctor who can take a look at you and feel it.
Depends on where. Very few bumps on your neck end up being thyroid cancer and far more are enlarged lymph nodes. But it really depends on exactly where in the neck this bump is located and a doctor can examine it and tell you if the bump is located within the thyroid gland and if there is any reason to be concerned.