Can you tell me about what it's like to have a stone in their salivary glands?

Try this. I have had some patient success with this technique. Suck on the most SOUR sour lemon drop you can find. If the stone is small enough, the build up of saliva will push the stone out. It can take several attempts. If unsuccessful, see an Oral Surgeon or ENT (Otolaryngologist).
Pain,congestion . It can hurt from congestion of the gland from presence of the stone in the duct,obstructing it,have it examined by a dentist or oral surgeon ASAP .
It can hurt. A stone can block the ducts that allow the saliva to exit the duct. If it doesn't exit there is a pressure build up. Pressure on nerve endings causes pain. See your health care provider ASAP.