DEAR FRIEND.
Thanks for sharing your concern.
penicillin along with flagyl (
metronidazole) is usually prescribed during
root canal treatment,as it takes care of both aerobic and
anaerobic infections very well.this is very much required in cases of root canal treatment.
In your case, if you are not finding comfortable using this combination then you can visit your
dentist and another set of antibiotics can be prescribed for you,like augumentin or cephalosporins etc.
Need not worry, you will be fine once your root canal treatment is completed. you will be problem free.
There are no nerves left in the tooth, to cause you pain after root canal,so relax,it will get over.
Meanwhile,if you wish, you can visit your dentist regarding the discomfort faced by with the present set of drugs and ask for a newer combination.
Also do frequent warm saline rinses and maintain very good
oral hygiene.this will help you in reducing oral infection.
hope it helps .take care.thanks