It is getting to the time when they are having stronger emotions that they don't know how to handle.
I repeat to my daughter....use ur big girl words. Mommy doesn't understand when u yell or cry, use ur words to help mommy. We repeated this for about 2 wks also praising her when she processed things w.o. getting upset. I was seeing much more getting frustrated when she couldn't do things by herself with this I role played alot. For example I would say I cant get my sock on, sometimes its hard and sometimes its easy. Dont get upset mommy, keep trying...stay calm and keep trying. If mommy starts to get upset I will ask for my helper buddy.
These ideas have seemed to work well w. my little one and I saw a good response after about 2 wks. Now she reminds me thruout the day 'Mommy do u need a helper buddy so u don't get upset?
They simply dont know how to respond to there inner feelings and it's always seemed to work for me to say 'this is how ur feeling, do this to feel better.'
Each child is different of course but I hope this helps alittle.
Be patient and best of luck! :