Hi.. Thanks for writing to us.. I have gone through your query and will try my level best to resolve it to the best of my knowledge and experience.. As per your complain it looks like there is deep decay in your teeth and it is causing pain due to irritation and inflammation of the nerves present in the centre of the tooth in a small space known as Pulp Chamber.. As your teeth are already advised for root canal treatment it is a further confirmation of pulp exposure.. Taking painkillers can provide only temporary relief and in case if there is pus formation below the root tips of the teeth then it can cause continuous pressure over the nerve fibres in that area and cause severe pain which at times even does not resolve with painkillers.. So as of now you can consult an emergency room and get injectable pain relievers along with oral painkillers like Tramadol as it can control severe pain.. You should however consult a Dentist soon and get a latest x ray of both the teeth done and then Root Canal treatment can be done after assessment of teeth.. Hope this information helps.. Regards.