How did a blood bubble grow inside oral cavity to return a responsibility

It may be caused by eating dry and hard food stimulation. If the blood bubble is small, it may disappear on its own. If the blood bubble is large, you need to go to the stomatology department for treatment. Use a sterile needle to prick it. Use compound chlorhexidine mouthwash. If it breaks naturally, you can use watermelon cream or tin powder for local application. If secondary infection occurs, you can take amoxicillin, cephalosporin, metronidazole, tinidazole, etc. orally. The above health science knowledge is for reference only. Specific conditions need to be checked in a regular hospital and judged by a professional doctor. Do not diagnose or treat yourself.