19 months is an age when a lot of things happen for a little guy. He might be on the edge of a language explosion, he is learning that you are really a separate person from him and is missing you more when you are away, he is nearly 2 which is when a burst of independence happens, so he might be needing more attention right now because so many things are changing in his brain and body. OR, is it possible that he has an ear infection after all his sickness? Sometimes laying down makes their ears hurt more, so holding him upright might be relieving some pain for him.
So, if it isn't an ear infection, you might just have to "suffer" through some sleepless nights, snuggle him more, and when he is a bit older he will sleep better. My son (now 3) was not a good sleeper until he was more than 15 months. Those 15 months felt like they would never end, but in hindsight it seems like a LONG time ago that he was up all the time... now it is his 15 month old brother that is up! :)
I am not a "cry it out" Mom. I am a "they are crying because they need me" Mom. As long as you are getting the sleep you need, I suggest doing what works for your family.
My sister in law gave me wise advice at my baby shower... she said I can apply it to anything when it comes to my kids... "This too shall pass". He will sleep again.