Hi.. Thanks for the query.. From your explanation it looks like the white coating on tongue, sandpaper like feeling and difficulty swallowing is appearing to be most probably due to fungal infection over tongue causing Oral Thrush.. If there is an appearrence of hairy growths on tongue then it can be overgrown tongue papillae.. So first of all you should consult an Oral Physician and get evaluated and your tongue should be clinically/visually examined.. If there is Thrush then antifungal medications can be advised like Nystatin mouthwash, Candid mouthpaint, Clotrimazole lozenges and plenty of probiotics intake.. If it is just overgrown papillae then regular cleaning and eating hard foods like carrots and apples can help.. If there is dry mouth then chew sugarfree chewing gums, use specialised mouthwash like Biotene and mouth lubricants like Oralgel.. Hope this helps.. Regards..