Tumor, Infection or bruise.
The lump on the back of your neck would be a part of your spine.
Neck mass is also called neck lump. It causes respiratory infection like cold or sinusitis. The lump mostly occurs in infants and children.
every guinea pig has a lump on the back of their neck, im not sure what it's for tho... but it's nothing to worry about
The large lump is more than likely a knot from the accident. It may be bruised tissue as well. It would be wise to consult a chiropractor for a specific diagnosis.
If you have a hard lump on the back of your neck, it could be a cyst. It could also be a form of a boil. If it does not go away, you should have it checked out by a physician.
Could be a lymph node.
A pea-sized lump on the back on the neck that moves could be a node. However, it is important to get nodes checked out to ensure that they are benign.
WHAT IS WRONG WITH YOU?!?! Take it to a vet ASAP!!!!!!!!!!!
It could be an imbedded tick.