Old folks here say that the baby is hexed when the baby goes on incessant crying for no reason at all. The first approach is to give milk and the next is to carry the baby and walk. If those things don't work then there's probably something wrong. And if you cannot find that the baby has a tummy ache then wait for the baby to vomit.
Well, the baby could be hexed, or maybe just suffering from a random body discomfort. I think after giving relief and medicine and after consulting a doctor, if the symptoms don't improve the baby could be hexed.
Hexed or not, incessant crying is indication of something definitely wrong. Ideal sequence to check would if the baby is hungry or has spoiled his nappy, or is having discomfort in his stomach due to gas. So address the need accordingly and mostly often, the baby will calm down and stop crying.
I think sometimes the baby may sense danger but am not sure about that or the baby wants your attention.