The reason for you being on antibiotics is not mentioned. Did you undergo any dental procedure for which local anesthesia was given on your upper jaw. The area you mentioned of swelling could be because of
1. Severe infection in that particular region.
2. hematoma which could be caused by injecting LA in blood vessels (nothing to worry as it subsides by itself in 7-10 days)
Next Steps
please visit nearby dentist asap
Health Tips
if infection or hematoma is the reason for swelling, please do not use hot water or warm compress as it tend to increase the swelling
avoid eating spicy or hot food.