submandibular gland swollen and hurts

After contacting Lyme disease years ago it sent my body into a storm of health issues which included a chronic sore throat. About a year ago my tonsils atrophied and I can no longer see them. At the same time my submandibular glands swelled up and hurt. The sore throat is gone but the painful glands are now constant along with constant post nasal drip and throat clearing.
I did have an ultra sound which came back normal. I haven’t been able to get an answer as to why this is happening. I never feel well. I wish I knew what is causing this and what to do. I do salt water gargle, neti pot rinses, saline sprays, good oral hygiene,
I saw an ENT last year who offered to do surgery to fix a collapsed nasal valve with Latera Stents but my insurance denied this because it was deemed experimental.
Has anyone experienced constant painful swollen submandibular glands, found out a cause and had any success getting this under control?
Thank you for any help.