Why Does My 2 And A Half Year Old Son Wake Up From His Afternoon Nap In A Really Bad Mood And Cry And Throw A Tantrum For The Next 30 Mins After Waking?

It doesn't matter how long he has slept for or where he slept, he wakes up and can be fine to begin, then after 5 minutes or immediately upon waking, he starts crying unconsolably and then that turns into a tantrum. He only wants his Mum and even then he is hard to console. This goes on for about 30mins every day after his afternoon nap!