Desperate for wise advice, please! ?

I have a 2yo boy and a 4yo boy who share a bedroom, and for the past couple nights they have been waking up around 1-1:30am and staying up for an hour or two. I am currently 26 weeks + 2 days pregnant with our 3rd boy, so this is very disruptive to my much needed sleep pattern, and is messing up my children's daily and nightly routine too. The thing that is so frustrating about this is that I have been a firm believer in sleep training, and in fact they've both been sleeping through the night without waking up since they were 2-3 months. Here's the thing; my boys have not been feeling well for the past week, and I took my older son to the urgent care with an ear infection yesterday. But this isn't the first time they've been sick, so I don't understand why they're suddenly thinking they need to be up and talking or playing at these ungodly hours! We tried putting one child in our room and leaving the other in his room, but the one who gets left alone sits at the door and cries, and the one in our bed will think it's time to chit chat with us. We leave the bedroom doors open so they're never left completely alone or in complete darkness. We have worship or smooth jazz instrumental music playing all night. If we turn the music off, we get tears about that. My husband is suffering too, because he works an extremely physical job (construction) early in the am. What do we do? How do we get our children back on a sleeping regiment? How do we get them to stop conversing with each other at 2am? How do we make them understand the importance of sleep? This mama is so tired, and if this doesn't stop soon, I'll be cranky and temperamental as well. Please help!