After having salivary stones for over 25 years, I finally found complete and total relief by taking vitamin k2. If you doubt, do the research, it makes sense. I am just relieved from having periodic swellings in my neck/under my tongue. I had become very adept at manually pushing on my neck and forcing the stones through. As fellow sufferers can relate, the stone would feel like a shard of glass when ripping through the duct! Stone-free for close to 6 months now with the vit.k2!
I dealt with the submandibular gland. Man did it hurt, especailly after eating. I stayed on apple sauce, pudding, & jello. I did the antibiotics all that did was give me oral thrush.
They finally did an ultrasound on the area; they discovered a mass, two enlarged lymph nodes that had grown in size and a calcified ligament. I had surgery and they did discover the gland was infected badly. (Sialenditis- sp?). They removed everything and all better now....
I dealt with the pain for 3-4 months..long story on why so long.
Assuming your diagnosis is correct, then aside from taking the antibiotics you can also try warm compresses, plenty of (non-alcoholic/non-caffeinated) fluids, massage and sour candy (to stimulate saliva production). Otherwise you just need more time.