I have a sore white bump inside of my mouth on my jaw but it's not really bump like.. it's flat.. red on the outside and on the inside it is white..

Examination required: To see of there is any adjacent contributing factors, and swap and culture / biopsy may be required

Hot compresses: Using hot compresses and rinsing with tolerable warm to hot saline water may help. Depending on how big and how long you have had it you want to seek a professional to observe it. Most likely it is infected. White blood cells being present as well as redness are both signs of infection.