not to frighten you, but she may be having seizures. that is what my 11 year old son does. Getting a doctor to HEAR your conserns will be a nigh mare in its self.
A sleep study will answer this if she is.
A developmental doctor would listen to you.
good luck
The shouting may be because of several things, pain is one, you do not say how old she is, attention seeking is another, hearing difficulties is one also. sign language is a must for getting through to any one that has limited communication skills. It can be done in an emergency by using pictures and words together, DS children are not stupid, they just have a hard time communicating their needs and frustrations. Patience with her and spending time looking for the answers she is looking for will help. You also did not say what the surgery was for. Most DS children have excellent cognitive powers and get really frustrated when no one understands them. Include her as much as possible in all family activities and let her know that she is loved. leaving her alone all the time gives her nothing to relate to, help her keep busy , teach new skills and give her some things that she can work with. will check back later with this .
You need to speak to a therapist who has experience working with children w/down syndrome. Also, check with her doctor, and if she doesn't have a good enough one call around til you find one with extensive experience.
How old is your sister?
Does she speak sign language?
I personally think the best thing a family can do with a child with down syndrome especially, or any child. is to begin teaching them sign language from birth, because often a child can use that before they can speak. I've heard/seen of children as young as 6 months using basic signs for hungry and play...
when my son is born (diagnosed with D/S) I'll be teaching him Sign Language from the beginning.That way if his speech isnt developed well enough within a year or two he can use sign to communicate any problems, fears, or worries he has.