HELP! Split nights 1 year old

12 month old DWT 7am. Approximate schedule (daycare driven) is 5/5 but he often is up way before DWT so results in more like 7/7. We’ve been having issues where he is up for 3+ hours hysterically screaming in the night. I don’t think he’s in pain from teething because he is totally fine and happy in the day. Sleep trained and goes to sleep independently. How do I figure out if he’s over or under tired or if this is just a sleep regression we need to duke it out through?