What would cause chronic ear infections in the same ear in an adult male?

[Lclulu]

My husband gets about 3 ear infections in his left ear a year.  He had to have a sinus reconstruction surgery on the same side of the face.  His ear infections spread quickly and are very painful.  Could this be due to the sinus surgery?  He sees an ENT doctor, the same one who did the surgery, and he just treats the ear infection but has never associated the surgery with the ear infections?  Should we get another opinion? A CT scan?  Thank you.