2 yr old sleep regration? Anyone?

My son just turne 2 a couple of day ago buts its been a couple of days were he has been refusing his day naps he used to take 1 hr nap in the morning and 1 hr nap in the afternoon. He started to only nap for 30 min and lately only once a day but tonight he been up for and hour and a half and he is crying on and of in his crib we have gone in a total of 4 times we rocked him and hes is calm get super sleepy but as soon as we put him down he starts to cry. And im like whats happening he is such a good sleeper normally he goes to bed around 8pm and sleeps throughout the night without waking up until 7.30am . Anyone else going tru something similar?