Hi.. Thanks for the query.. As per your complain redness of throat and back of tongue along with bad odour can be due to causes like throat infection, sinusitis, tonsil stones, acid reflux etc.. So my suggestion is to first of all consult an ENT Physician and get evaluated and a thorough clinical examination should be done followed by appropriate investigations like throat swab culture, sinus x ray, blood tests etc depending on suspected cause so that treatment can be done accordingly.. As of now you should start gargling with a flavoured mouthwash twice a day.. You should chew flavoured 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.. Hope your query is resolved.. Regards.