Hello, I went through your query, yes all the reason that you are given can cause this itching in throat, probably allergic rhinitis. If you have moved here recently then this change in weather, dust, is causing this allergy. If the symptoms are not daily, but get often like once in a month, could be due to viral infection (since it's ac room). Please consult an Ent surgeon first to examine for any infection or any deviated nasal septum (cause frequent allergies).