Thanks for writing to us.
From the details mentioned,its clear that plastic freezer has damaged due to chemical burn
But usually,this condition do not have any relation with metallic taste
in mouth,unless the poisoned food material in freezer has ingested.
Gastric lavage has to be done.
I would suggest you to take fresh vegetables as well as meat until the symptoms subside.
Antibiotics has to be administered to relieve underlying infection.
Meanwhile,please do visit a dentist
and get a thorough clinical check-up done.
Grossly decayed or impacted teeth has to be extracted ,if cannot be saved.
Gargle frequently with lukewarm saline.
Hope this helps.