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Anxiety as well as excitement can cause this feeling... does she have symptoms of anxiety such as nervousness? Anxiety can lead to hyperventilation which can lead to less blood flow to extremities causing weakness , heaviness and numbness.
While not specifically mentioning anxiety, my wife has asked our daughter whether she is getting tense. She says no. She doesn't seem to be hyperventilating, at least the way one thinks about hyperventilating.
When this is actually occurring have you noticed if she seems to be tense?
In the absence of abnormal findings.. anxiety is a possibility.
She does seem tense. We will explore this avenue. Thanks for your help. I will accept your answer.