I find with my DS, if he hasn't been outside to play, he takes longer to go to sleep. He's such a high energy boy too so it's difficult to tell his tired signs. We mostly go by time. If he's been outside running around or at the park, he's asleep within minutes of going into his cot. If he's been sitting around watching TV or in the trolley while I'm shopping, he takes a lot longer, often close to an hour.

My DS loves having a pillow so it could be time for that. We've recently taken the side off his cot so he can climb in himself (we have a safety rail and there is a small gap he can climb through at the foot of the cot). He loves it and will climb in happily. My DS is a little older than yours though.

Is he screaming in distress or just having a little sook? Since he was in the same room as you on your trip, he's probably used to having you there so maybe a slow introduction to being alone again will help. Try leaving the room when he's almost asleep and gradually make it earlier. I found with my DS, he actually went to sleep quicker when we started leaving the room. Sometimes he'd cry out and I'd go back in and let him know I was nearby and he'd lie down again. If we stayed in there, he'd lie there watching us and wouldn't close his eyes. It was like a game for him.

Maybe the sleeping bag is restricting him? Have you tried PJ's?

Good luck.

ETA: We got DS's cot pillow from Ikea.