Help! My Puppy Woke Up From A Nap And Was Very Aggressive And Afraid!?

I have a 13 week old cockapoo puppy who woke up from a nap late last night and totally panicked. I was standing about 6 feet away from him when he woke up with a start, and ran to the corner of our bedroom alternating between blood curtailing screams and growls directed at me. He also smeared a bit of poop over the pillows as he ran. It took him about 20 seconds to calm down, and then it was like a light went on in his head. He abruptly stopped screaming, and came running towards me shaking. He then hid under my legs for about 10 minutes. I tried to go to sleep about half an hour later, but he refused to lie down. It was as if he was on guard. We were up for at least 3 hours trying to get him to relax. Before last night we had never had a problem with him going to sleep.
He is the sweetest puppy normally, but last night I was truly afraid he was going to bite me. This happened once before, but to a much lesser extent. He woke up from a nap and screamed, but it only took a few seconds for him to calm down and come cuddle me. I don’t normally have a problem waking him up from naps. I call his name and he opens his eyes, tail wagging, and wants to snuggle. I have only used positive reinforcement to train him, and he is very cuddly with me normally, so I know he isn’t actually afraid of me. It seems like he forgets who I am…
Has anyone had any experience with this type of behaviour? Is it possible he is just having really bad dreams and he will grow out of it? I am at a total loss as to what my next step should be and could really use some advice!
Thanks so much, BP