S.H.
Its a phase!
It will pass! Believe it or not.
My kids, when they were that age, would even run away full-on sprinting, and scream at diaper changing time. Oh well... sometimes I even had to stop myself from laughing. It was hilarious!
they do get "dramatic." And yes, I had to catch them, lay them down, straddle my legs around them and put my legs on their arms... hold their legs with both my arms, and using just my hands, take off their diaper, slide the new one under them, clean them up real quick, and strap the new one on. Like a stealth jet. The WHOLE time, they are screaming and twisting their torso and balking and oh boy, what an ordeal!
But it passes. It DOES. Saying stop will not make them stop.
Use distraction.... with anything that will keep his hands busy and his eyes on the object. And you will get to be SUPER fast about the process. I always get all the things ready before hand...the diaper, the diaper cream, the wipes... THEN I go catch my kids, and just do it.
Sometimes, just try and CHANGE their mood... I would make my kids laugh and do silly things with my face and voice to "trigger" a switch in their protesting.
It will pass. Then other phases will come up! LOL
All the best,
Susan