At 19 months, there are a few things to keep in mind. It could still be teething, and he could be cutting molars. Cutting molars is so much more painful than front teeth (that are sharp and pointy). So it is possible that he's in more pain.
It could be an ear infection. That's very common at his age.
it could also be that something is scaring him. His imagination is so much more vivid and active at that age. He could simply be scared and needing comfort.
It can be a challenge to figure out what's upsetting him, but we always began by responding to cries immediately (we never let them cry it out or even cry a bit). The first thing we try is just soothing. If they are in pain, soothing will only get you so far, so it's kind of an indicator of something more. If they are scared, soothing will usually do the trick. Still, when they are too young to talk, it's always a challenge.
It's great that you are wondering, could he be ready for a change in routine. Mine were always ready for a change in routine shortly after we had finally found one. But as they get older, they get much flexible. And they can talk and tell you what's wrong :-)