What Causes Severe Pain In Eye Irritating The Nasal Passage Post Cataract Removal?

Hi my mother is 84 indian she has had eye cataracts removed a few years ago, suffers high blood pressure but controlled, is on thioriod tablets but does not have diabetes or heart problems. She is suffering very sever eye pain like pin in the back of the eye which is irritating her nasal passage and hurts when talks or eats. She was diagnosed with lacking vitamin B and had injections to correct. She has eye drops and tablets but no resolution this has been going on for few months. Doctors or ophthalmic specialists can t find anything wrong but possible dry eyes. Please advise