Toddler won’t nap


Suddenly my 21 month old won’t nap. I’m a stay at home mom and 8 weeks pregnant so really look forward to nap time so I can get some much needed rest. He has always been a bad sleeper but usually will nap, I don’t know why he thinks he doesn’t need to anymore. He usually takes one nap a day for 1-1/2 to 2-1/2 hours but twice this week he will lay down but won’t sleep. I don’t know what to do. I sit there by his crib and hold his hand while stroking his back and sometimes sing twinkle twinkle to him which usually works but isn’t currently. Anyone else’s kid do this? Please tell me it’s just a phase.