my daughter can just from no where starts screaming very loud with such intense anger for no reason, she can also do this when we say no to her or she can't get her way. So its confusing when she starts crying without any cause.

Behaviorally/emotionally, the meaning depends to some degree on how verbal the person is.
Crying can also express happiness,anger, relief, inability to know how to reply , & often a mixture of these. (Many people cry at all weddings...) It can be a positive sign that she trusts you. Just holding the person can sometimes be enough.
Biochemically, it can be a sign of high prolactin.
Many consult a spectru,specialist therapist to be sure.

My son did this for a while, he isnt talking yet so it took 2 weeks of investigating. Finally found out he was chewing on the inside of his cheek so bad that he had a couple sores that were burning when he would eat or drink. He now has a basket of chewies to help prevent that. He also use to cry only in the summer at lunch time at the table...my husband discovered he was scared of his shadow lol. It takes some investigating sometimes.

Inappropriate laughing or crying is a sign of autism. My daughter laughs at nothing sometimes. It always reminds me of the old movies with crazy people laughing in an insane asylum. It's not all the time but hope she grows out it some more.

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