1. Looks like a dental abscess
usually does not cause pus drainage
from the gums or around teeth unless there is an oro-antral fistula.
2. On the other hand, since this is an upper tooth, a part of the thin bone between the upper teeth and the maxillary sinus above them may be eroded or dehiscent (missing); a dental abscess may lead to sinusitis, which may then co-exist.
3. Get a dental examination and dental x-ray done immediately for a quick diagnosis.
4. Both these conditions may require antibiotics in addition. Get these under medical supervision. Pus culture may be necessary.
5. The abscess may require drainage and treatment of the offending tooth.