hi M., i am new here, but my daughter is going through the same thing with naps. she is 16 months and already in that "terrible two" stage. up until recently she was taking 2 naps a day. 2 hours in the morning and 1 hour in the afternoon. that changed recently, so we went down to one nap a day. now she is now switching times around... sometimes she'll want one in the am and sometime in the afternoon. it is very frustration to say the least. when she doesn't want her nap she will fight it hard. she will lay down immediately and when i leave the room she gets up screaming. i let her try to cry it out, but if it goes past 20 min or it's a different cry, i get her up. if possible we go do an activity to get it out of her system. sometimes she ends up being so tired by 3/4 pm from fighting the nap and not having one, that she eventually will take one. i would try two options: set a nap time that works for your schedule. try to at least put him down at/or around that time daily. even if he plays in there, he's knows that's "nap" time. some days he may fall asleep. if he doesn't, you can get him when he cries or let him cry it out depending on your methods. if he insists on no nap, let him play till he's exhausted or unbearable (HAHA) and try to put him down later in the afternoon, even if it's only for an hour. i hope that helps. i am certainly no expert, but sometimes this works for me. i wish you luck dear.
L.