Adult corn snake refuses to eat

Hello all,

Brand new member here and this is my first post. I have a corn snake that is about 5-6 years old. We have had him for 3 years. During that time, he has never had a problem eating (frozen/thawed large mice). He typically eats every 5-7 days without fail. The exception to this over the past 3 years has been in late Feb/March for about 2 months (mating season). Overall, he has been in perfect health and is usually very active.

About 5 months ago, he stopped eating. Nothing in his environment or food source changed. After 3 months of not eating anything, and after running out of ideas, I tried two live feeder mice. He immediately ate both of them, once right after the other. That was two months ago. Since then, he has again refused to eat the frozen/thawed mice. We have tried to feed him roughly once a week with no luck. During that time, we took him to a vet to have him checked out. The vet said he appeared to be very healthy, but did appear skinny from not eating. The vet recommended providing more warmth in the tank, which we did.

Today, I tried another live mouse and he again ate it almost immediately.

I am looking for any ideas on getting back on his frozen/thawed mouse diet. Not only do I have about a years supply that I have already bought, but I don't want the snake to get hurt from the live mice.

I completely understand the downside of feeding live mice so I am not really looking for advice on that.

I appreciate any help. Thanks!