The sore is actually on my palate, ans there is a bit of swelling and redness.

Sore: There are literally scores of reasons for mouth sores, including, but not limited to, viral/bacterial/fungal infection, trauma. burn, cyst, oral cancer, blocked minor/major salivary ducts, etc. Please see a General Dentist, a Specialist Oral Surgeon, or an Oral Medicine Specialist for an examination/imaging/lab tests to determine differential diagnosis and appropriate treatment plan.