Good night. Girls, today I couldn't put my son to sleep all day, he cr…

Good night. Girls, today I couldn't put my son to sleep all day, he cries and won't sleep. He only fell asleep for 30 minutes on a walk. I managed to lull him to sleep 30 minutes ago, now he starts fussing in his sleep and opens his eyes, I rock him again, he falls back asleep and this repeats several times already. What do you think might be bothering him? Today is such a heavy day, I feel like the night will be just as bad. On his belly he used to behave like this so much less. What could it be?