Hi.. Thanks for the query.. Swelling or thickening of tongue that comes and goes is most probably pointing towards Allergic reaction that is causing Allergic Angioedema of tongue.. There are a number of causes like food allergies, drug reaction and even environmental pollutants can also be a cause.. You should consult an Emergency room and get evaluated. You can be advised a blood test to confirm the diagnosis.. In case if it is allergic reaction then the cause of allergy is ruled out.. You can be advised to avoid exposure to allergen and if at all the symptoms recur then you can be advised anti allergics like Levocetrizine, loratidine etc along with steroid shot if the swelling is too much to interfere with breathing.. Hope this helps.. Regards..