hello and welcome to hcm forum,
i am glad you wrote in, first of all , i would like you to know that sometimes prolonged use of certain antibiotics can cause ulcers/soreness in the oral cavity, but you mentioned that you took antibiotics only for 2 days, therefore antibiotics are not the cause.
you have not mentioned, since how long are these sores present or do you wear dentures(partial/complete) or not, i assume you don't.
1) I would recommend you to use an antibacterial*(
betadine) mouth wash, twice/day for a week.
2) avoid spicy food for a week,
3)do not apply any topical medicament over the sores until prescribed by your concerned doctor.
do not worry, sores will disappear within 3-5 days,
but if in case, there is no relief ,then kindly visit your doctor.
i hope i answered you query,
i wish you good health.