BLUE TONGUE SKINKS

I recently got a 2 year old male Northern blue tongue. He has been great, very docile, the perfect pet. It's getting cold here in Indiana so as expected, he has stopped eating very much- I haven't been able to get him to eat anything for a few weeks. This evening when I was doing work beside his cage, he opened his mouth as wide as it could go and i noticed he had a lot of substrate in there that he was trying to get out. He opened his mouth for me and I carefully was able to get most of it out without pushing any farther in, and he continued to kind of force the rest out of his mouth. just when I thought he had gotten all of it out, he started opening his mouth really wide and making a gagging motion. Since then he has been making weird wheezing sounds- it almost sounds like hiccups except that instead of taking air in, he is expelling it. you could also compare the sound to a duck's quack. it's very strange. every few minutes he will open his mouth and gag, and then a second later wheeze once or twice. It has gotten less frequent as time has gone on, but i'm still worried- thinking about calling my local exotic vet. Any suggestions?

Absolutely get him to a vet. Any sounds abnormal sounds when breathing are of great concern. Depending on what kind of substrate it is, he may need care from the vet to try to prevent impaction as well.