Part of Scale being rough

Hello. My one and a half years old Gold Dust Corn Snake's scales is rough and unusual (part of it, not the whole body), I just realized it this morning. It has been eating fine, but very active recently, it's active even during the day when usually it will be active during the night. Its last shed was last month (a complete and full shed, I made sure there wasn't any stuck shed on its body the day after it shed). I asked my local reptile store for help, they think it's stuck shed and recommended me to give it a warm water bath everyday for 15 minutes until that patch of rough scale is gone, and also to clean the enclosure.

The rough scales part is located at my corn's upper front part (near the head), it's not smooth as usual, and the scales are like spiky and standing. The mice it eats are all frozen mice so there's no way it could be an injury from the mouse it ate.

May I know what caused it to be like this? And how can I treat it? Any help would be appreciated. Thank you!