I have a 15 months nephew. he seems so angry these days and very emotional (crying and shouting) what can we do? and is there any physilogical cause?

Tantrums?: The only way to see if there's a medical cause is to see his doctor. He may be having tantrums. Often, kids act out to get attention, even negative attention;withdrawing attention from the misbehavior (i.e., timeouts) & giving positive attention for good behavior helps. Distracting your child when you see misbehavior start can head it off, too. Ensure he doesn't get overtired or famished.

Possibly: This is not normal for a 15mo. Something is clearly bothering him and a helping professional with experience with young children should be seen.