Swollen right submandibular gland, little pain, happened 4th time, goes away in 1-2 days. What could it be and what kind of doctor should I see? Ent?

See ENT. Could be a small stone causing minor blockage of the gland's duct or some inflammation of a lymph node associated with the gland. Not likely anything sinister if it just comes and goes. Probably worth getting it checked by an ENT doc, maybe a ct scan for peace of mind.
Yes. It would be wise to seek the opinion of a primary care physician or an ENT in this case. Primary concern would be a chronic or relapsing infection in the region. This type of gland is often related to dental problems, sinus and other upper respiratory problems, skin and hair issues as well. There are many other conditions associated with this as well. Please get it checked.