You are right to test: Your gut is telling you something is not right, and your child is expressing a negative physical and emotional response to her math. The answer could be anything from "it'll click eventually," to "she's right where she should be," to "she learns differently than her instruction assumes," to "she has a learning disability." You can't know under you have a full investigation into her achievement and how she learns. No matter what, I'd advise your tackle the negative associations to math and the physical responses directly. Does the teacher know about the headaches and that she "hates math"?
FWIW, my DD just went through remediation for dyslexia. She went from slightly below average to exactly where her verbal IQ would predict with a little bit of intervention (4 months of school services and then an awesome teacher). She advanced between 6 and 10 grade levels across most areas of writing and spelling in about a year. We wouldn't be here if it hadn't been for the neuropsych exam 2 years ago. We went into the testing because she was crying every night over writing and she performed below the level we (and she!) thought she could.
