As you said, you are having cystic lesion on lower lip, internal area.
With your history , I feel that you are having mucous cysts.
The cysts are containing mucin, sticky fluid.
The lesions develop due to blockage of ducts of salivary glands.
Exact cause is not known, but trauma might induce the disease.
Cust may rupture, reduce in size and come back again. And this happens repeatedly.
In my clinic , when such patients are found, I usually advise to keep patience, to wait for few months for self healing. If it feel embarrasing, then the area containing cyst may be excised and stitched under local anaesthesia.
However, you consult nearby dermatologist
for perfect treatment.
I hope you got my answer.
Dr. Ilyas Patel MD