I know you are having a possible evaluation but I still think you need some strategies to deal with the current issue. First I would not use the crib as a "time out". The crib should be associated with sleep, safety, and his own space. If it is used as a punishment it could pose issues with napping and bedtime and confusion with being in trouble. Children older then one can have "time out" but it will look different. They may not be able to sit in the space but you can designate one. My suggestion would be to do something like this. Once your son bites you come over calmly and say in a firm voice, "no biting." Then remove him from the situation and place him in the designated time out space such as in the hall on a small rug or next to the couch or somewhere you can move him quickly and still be in ear/eye shot of your daughter. Sit him down and have him wait one minute and no more then one minute (one minute per age of child). You could say, "no biting" one more time as well. He may squirm stand etc as long as he is in that spot it doesn't matter how he does it. You may even have to hold him. After it is over you could walk him over to your daughter and find a resolution to the original issue. He may not understand this part yet but he will and your daughter will see good problem solving as well. I would do this EVERY time he bites even when out of town. Just roll up his little rug and take it with you. Consistency is huge. It sounds communicative in terms of his frustration. If this is the case try to figure out some language he could use to say what he wants instead of biting. Regardless if he gets a diagnosis of Autism or not, which I pray he doesn't, you can still use these strategies. I wish you luck and please know that most if not all toddlers have some sort of aggression whether it be biting, hitting, pinching, slapping, or screaming. Most behavior is communication and our little guys understand a lot more then they can tell us at this age.
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