What is this large white sore on my tongue started small now grow in larger not bumpy?

Need more info.: Is it painful ? Do you have any dental appliance? E.G. Bridge or partial denture ? The cause might be from trauma like sharp edges of dental appliances or infectious like aphthous ulcer. See a dentist for an examination.

Canker sores: Canker sores, also known as mouth ulcers or mouth blisters, usually heal on its own in about a week or two. You can try warm salt rinses. If the sores continue to persist, or are large or painful, visit your dentist. Depending on the nature and severity of the sore, your doctor may prescribe antimicrobial mouth rinses, corticosteroid ointments, or a prescription to reduce the pain and irritation.

Needs to be seen: The bottom line is that if it remains more than two weeks or you are uncomfortable enough to want relief, you will have to see a dentist for a one on one clinical evaluation. It could be many things, most of which will go away on their own within that time frame. The ones that don't require a definitive diagnosis and appropriate treatment.