Tongue has sores and feels burnt. Third day of Invisalign treatment. Any advice to ease the pain? (Photo)

We are sorry to hear you are uncomfortable! To help ease your discomfort rinse with warm salt water rinses (without aligners in) several times (at least 4 times) through out the day. 
* one table spoon of salt in 8 oz glass of warm water 
If you are able to pinpoint where the aligner is causing irritation and you feel comfortable doing this, you can take an emery board (nail file) and carefully smooth the area using the rough side of the emery board first and then go back over that area with the smooth side of the emery board. 
I hope that this helps with your concern and discomfort from your aligners.
Best,
Dr. Paul J. Styrt, DMD,MPH, MS