Hi.. Thanks for the query.. The white lumps at the very back of the tongue can be due to infection and inflammation of the Circumvallate Papillae that are large papillae present at the back one-third of tongue in a typical v shaped pattern. It can occur due to causes like oral infections, acid reflux, throat infection and post nasal drip, burning with hot foods, upper respiratory tract infection etc.. So first of all you should get it clinically examined by an Oral Physician.. A course of antibiotics, anti-inflammatory medicine and antiseptic mouthwash rinses can help in resolution. Also do warm saline gargles. Avoid irritant and spicy foods. Maintain meticulous oral hygiene.. Hope this helps.. Regards.