Could just be a growth spurt AND a period of adjustment.
My son went through several of these. Very similar to what you are talking about.
I would make sre he is more active during the day. Maybe keep the nap for now if he still seems to need it. Later you can play around w/that nap & see if you can shorten it, change the time or do away w/it for a bit.
My son did that for a few months: didn't nap, then went back to a nap, ajdusted time then no nap etc.
Try making sure he is more active during the day when you get home from daycare.
Try going in at 12:30 & be quiet but just soothe him.
Make sure he won't take a drink of milk/water or breast milk.
Sleep adjustments can happen several times around this age.
Just work with it & try tweaking it in different ways.
If one idea doesn't work, try another one.
Hang in there....it will level off & get back to a "norm".