My Betta is always hiding and doesn’t eat much

So my betta Harvey lives in a 10 gallon which he got put in around November. Before this he was in a lot smaller of a tank. When I first put him in the ten gallon he acted sort of strange which wasn't very crazy because he had just been moved and introduced to some Pygmy cories. I think he was eating normally pretty much up until recently? He likes hiding in his log or somewhere where I can't see him usually. And when I feed him he comes up to the top takes one nibble of food then swims back to rest on the bottom. There's not bad water flowing or anything stopping him from going to the top, he seemingly used to just fine. I'll send parameters when I can, tomorrow. The only things I could think of that are stressing him are maybe his light or the fact that it's pretty cold right now? He has a heater but I suspect that the tank is still a little but on the cooler side? It's like 74-76 usually (according to the sticker thermometer). I just don't want anything to be horribly wrong with him for whatever reason. I watched a video saying bettas that hide and don't eat are going to die very soon or something...