Hello and welcome,
Thanks for posting your query.
First of all let me tell you that please do not take antibiotics without medical supervision.
Pus discharge from the gums as well as metallic taste
may be due to-
Pericoronitis due to impacted wisdom tooth
developed due to poor oral hygiene.
Deep dental caries progressed into abscess formation.
I would advice you to get your teeth cleaned.
Pus has to be drained and curetted.Decayed teeth has to be restored.
Pleas do visit a dentist
for further reference.
Grossly decayed teeth has to be removed.