Is my dog depressed or sick

My dog has been acting different the last two days, he refused to eat food even meats, and he has been sleeping alot like napping through the day, waking up and then going back to sleep. He has been off too lately like not barking at the neighbours and it's unusual because he often barks at people for just a footstep, and not that energetic like before, before the last two days he would dash out the door before you could even close the door pulling tightly on the leash and sprinting as fast as he could but now he would go slowly trotting the way and being way more quiet, plus he has been sniffling like a drop of sniff would come down his nose, lmk if you guys have any ideas.