Is it possible for me to develope cancer in the mouth or salivary gland if no one in my family have any history of cancer at all?

Low risk: Without a family history you are at a low risk for these cancers. To reduce your risk further, please abstain from use of tobacco and alcohol.

Unlikely genetic: Genetic link in oropharyngeal cancers is not established, although higher incidence seen in certain anemias like fanconi etc. At your age , don't worry , smoking , drinking , tobacco & betel nut chewing , & oral hpv virus infections are all contributing factors. So with good healthy habits along with good oral hygiene you can minimize the risk.

Yes: Other factors including social carcinogenic agents (smoking and chewing tobacco) and well as other factors may predispose you to oral cancer.

Oral cancer: Risk at your age is very low. Minimize your risks by avoiding tobacco in all forms and excessive alcohol consumption. It you do both, the risk rises greatly. All patients should get a full head and neck soft tissue screening along with routine dental check-ups every 6-12 months. If your own dentist does not do that as part of his\her normal protocol, ask or change dentists.

Posible, but : not probable. See your dentist. They are experts in maxillofacial pathology disorders. Your symptoms should be viewed as a group of related conditions or separate issues. Call your dentist for evaluation appointment. Good luck.