Need some help

Lisa • Mother of three. Had first child when 19. She had a heart defect and other birth defects but is doing great now. Then had cayden two and half years later and finally my baby boy Skylar 2 years later.
I have a four year old son, he stays with me mon-fri then goes to dad's Fri night threw mon morning... idk if this is part of it but... he screams and cries at every little thing. I say getting your shoes on he cries, pick up a toy he screams and cries, he has so many emotional outbursts threw out the day. I don't know what to do it him, I can barely talk to him because he just screams or cries....I don't know what's wrong with him... I'm so lost....everyone gets frustrated with him fast because of his outbursts.