To determine whether the episode was a seizure, he had a short (25 minutes) and long (48 hours) EEG done. The short one came back normal and we are waiting for the results on the long test. He is scheduled to have an MRI done tonight to look for any developmental issues.
So, we're basically waiting for results right now (like always, it seems). If those tests (EEG, MRI, ultrasound and blood tests) come back normal - and we should find out tomorrow - then the episode will be attributed to him breathing in fluid after spitting up and we'll most likely be discharged. Fingers crossed this is the case and we can go home soon.