Hi It is not clear whether the last teeth is third molar or second molar... If it is third molar (wisdom teeth) you need to go for removal of the teeth as it is not used for chewing and eating purpose...... If it is second molar teeth then you need to go for root canal treatment of the teeth Both clinical and X ray investigaton  has to be made to rule out the cause

Hello As per your query. .. it could be the wisdom teeth that is troubling you .. so u can take an xray or radiograph ,through which we can assess the presence and severity of the infection and go ahead with fillings or root canal treatment accordingly. One suggestion is if its your wisdom tooth ,u can get it removed if there is infection .Anaesthesia would be given while extraction .. post treatment medications would be given . Hopefully u should have a speedy recovery.

First take and IOPA (X ray) and assess the severity of the dental infection. If you have sufficient remaining tooth structure it can be saved by root canal treatment.