It looks like an exposed bone or bony spicule which may be due to the stitches not done properly or removed before healing or loosen up and also may be because of the bony not smoothen before closing
There is nothing to worry about it
For now u can take medication
Tab Diclomol SOS (if there is pain)
M/W betadiene
Next Steps
See your dentist if there is no improvement in healing for 7-10days and also radiograph will give more clear idea about it.As of now it should heal of it's own not to worry
Health Tips
Maintain oral hygiene (brush twice)
Warm salt water rinses at least 3-4 times a day
Use of betadiene mouthwash 3-4 times a day
Rinse ur mouth everytime u eat
Keep that area clean, don't let the food lodged over there