If the pain is increasing, please visit a dentist immediately. If you really must wait a few days, be careful not to eat hard foods or put too much pressure on the left side. Use your right side to chew food. Avoid anything very hot/cold and sweet that triggers the pain. For increasing pain, you should never wait. Please don't look for home remedies and temporary solution, go see the doctor immediately. They will treat the pain and any swelling that might accompany the pain. The sooner you go, you might be able to save the tooth.

The pain that has been caused may be due to an infection at the root tip of the concerned tooth. As it is long standing it is advisable for you to see a dentist to assess and diagnose the real problem using an X-ray and other diagnostic methods.