Hi.. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain foul smelling breath or bad breath also known as Halitosis can occur due to a number of causes like poor oral hygiene, oral and dental infections, tonsil stones or tonsilloliths,post nasal drip, sinusitis, acid reflux,respiratory infections, diabetes etc.. The medications that he is taking generally does not cause a severe bad breath but you oesophageal bleed can be related as the cause for bleeding can be due to acid reflux.. You should consult an Oral Physician or an Otolaryngologist and get evaluated and a thorough clinical evaluation and investigations depending upon suspected cause can help in diagnosis.. Treatment of underlying cause will relieve the symptoms.. As of now he should start gargling with a flavoured mouthwash twice a day.. He should chew flavored sugarfree chewing gum.. Do warm saline gargles twice a day.. Limit the intake of high aroma foods like onion and garlic.. Drink plenty of water and maintain a good oral hygiene.. Regards.