I got a white bump on the inside of my mouth and it hurts. it goes away and then pops back up in a different place in my mouth. what is it?

Need to examine: It is difficult to say without examining the "bump". It would be prudent to consult your doctor.

Canker sores: are the most common oral lesions. Individual ulcers typically last 1-2 weeks only. They can be painful and can make eating and talking very difficult, but not infected. are the most common oral lesions. However, it is a good idea to visit your dentist to support the diagnosis.

Get it checked: See a dentist and get the bump checked. It is impossible to tell you what is is without seeing it. Once you know what is going on your dentist will also have some advise on preventing, treating , or reducing them in the future.

White bump: Literally hundreds of causes for white lesions in the mouth. Post probably aphthous ulcers. Can't tell, however, based on your very limited description. Call your Dentist or an Oral Surgeon. Alert them to your problem. Make arrangements to be seen the moment the next "white bump" appears. Good luck.