Afternoon Monster

Recently, Jackson has been having tantrums when he wakes up from his afternoon nap.  He's like a little monster.  Screaming, crying, pretty much flipping out for anywhere from 20 minute to an hour.  He wakes up screaming, and when I get to his room, he doesn't want me to touch him, then wants me to carry him, then tells me to stand up, then sit down, then starts faking a cough and starts choking because he's crying so hard.  And on & on. Total mess. So bad that I dread his naps. 

And some days, he doesn't fake a cough.  Instead, he starts moaning about his tummy hurting, or his ears, or whatever he thinks will garner the most sympathy.  Followed by his pleas for medicine.  And them I'm caught between whether or not to believe him.  The first few times, I fell for it and the minute he got a cough drop in his mouth, he flipped the switch from monster to angel.  But other times, I can't tell if he's crying wolf or not....?
Does anyone else have experience with this craziness?  There is no rhyme or reason to his post-nap tantrums. I've tried to pinpoint is it short vs long naps? How well he ate at lunch? What time he went down? 

In the little bit of research I've done, there is sleep disorder called sleep inertia, where the body physically wakes up before the brain does.  So you're caught between being awake & asleep.  He seems to fit the bill for the symptoms and hopefully its just something he'll outgrow eventually.