Hi! His routine looks good to me... his A times are a bit on the high side.. I'm at around 3.5 hrs-3.45 and he's 11mths. His morning A time he's up from 5am to 10am? ...they are a bit high. Is he OT during the day? I know OT can cause night disruptions and EWs too. Something to think about.
Teething? How about outside noise or light? With those cries you described, it sounds like pain... discomfort?
The times my LO did EWs was when teeth were coming through.
I would say developmental but when u say he wakes screaming the way he does... I would assume pain of some sort. Developmental would be more like waking and babbling, rolling around etc.
Hugs
hopefully this passes quickly!