Help! 16 month old refusing to nap!

B

Our 16 month old has started screaming bloody murder for nap time. I've tried putting him down at the normal time of 930, I've tried waiting until 10, 1030 but the result is the same. This God awful screaming when I leave the room. I let him sleep on me yesterday for 2 hours hoping it would give him enough rest to be able to calm himself down today. I have no idea what is going on. Is this separation anxiety? Teething? A Leap? Is he just being stubborn? All his other leaps have not been this bad or perhaps he has just found his very loud screetching voice? Any advice is welcome!