Hello,
Thank You for your query at DoctorSpring.com
I request you to upload a high resolution image of your tongue for me to be able to understand what kind of a blister you are having.
Such painful blisters can occur due to a lot of causes such as emotional stress, oral hygiene, vitamin b12 and iron deficiency, lack of sleep, stress, e.t.c But since you had sore throat before it seems more infective in origin. Even oral thrush needs to be ruled out.
Hence i can give you my opinion, once i see a picture of your tongue,
Regards.