I have a lump that dropped into my jaw just under my right jaw right below right below right ear lobe what could this be. i have had this happen once?

Likely lymph node: That location suggests a lymph node and could relate to an infection in the area such as skin, teeth or face. The parotid gland is above the jaw and in front of the ear so is in that area and an have infection or stone since it is a salivary gland. Other salivary glands can swell in that area as well.

Likely a lymph node: If it presented pretty rapidly, likely a lymph node- normal structure involved in response to local inflammation or infection. Hard to tell by your description, but could also be an inflamed salivary gland. There are several other possibilities which are less likely.