Hi.. Thanks for the query... Bitter taste in mouth along with sore tongue is all appearing to be due to Dry mouth or Xerostomia that can be most probably due to the side effect of medication which she is taking.. Anti-anxiety medication can cause dry mouth and the other symptom are seen secondary to it.. So my suggestion is that her medicine doses should be titrated or the drugs should be changed so that they can cause lesser side effects.. For now she can chew sugarfree chewing gum and use oral lubricating gel like Oralgel. Continuing Biotene mouthwash.. Avoid any regular mouthwash as they have drying effect in mouth and can worsen the symptoms.. If symptoms are still severe drugs like Pilocarpine can be advised for stimulating salivation.. Hope this helps.. Regards.