Hi.. Thanks for the query.. Metallic taste in mouth along with sensitive and irritated tongue is due to causes like side effect of any medication if you take, allergic reaction, dry mouth, yeast infection like Oral Thrush etc.. So first of all the exact cause needs to be ruled out. For this an oral examination and if needed an oral swab culture can be done to confirm the cause.. For now you should clean your tongue using a tongue scraper, gargle with hydrogen peroxide solution in water. You can also dip a soft toothbrush in hydrogen peroxide and water solution and gently clean the tongue.. Do antiseptic mouthwash gargles flavoured with mint/ menthol etc. Chew flavoured sugarfree chewing gum to mask bad taste..Drink plenty of water.. Avoid spicy and sharp foods.. Hope this helps.. Regards.