hi and welcome to HCM,
Accordingly to your history i can say you have got severe infection either in your last right molar tooth or the adjacent gums . This needs clinical examination and evaluation with a x ray
to confirm and accordingly treatment for the tooth or the gums can be done.
If the gums are inflammed ,you can go for professional scaling and root planing done by a dentist
At home you can use lukewarm saline water or antiseptic mouthwash like chlorhexidine
for mouth rinsing and gargling which gives soothing effect to throat and restores gum health.
For chest pain
on breathing you need to get an chest x ray done and consult a physician for evaluation and treatment.
i hope this helps,