Yes and no. I have a 2e child who has twice taken the WISC-IV and who is dx with inattentive type ADD and who may be dyslexic. Mine does not have issues to the extent yours does and her grades are higher, but all of what you mention is there, just not to such an extreme.
My dd's two WISC testings were 20 points apart with the first one being PG and the second, a year later, MG. Even with her MG testing, she had parts where she was at or above the 99.9th. I tend to think that her "true" IQ falls somewhere in btwn but possibly somewhat closer to the first than the second testing.
B/c she is so able, schools have never suggested a LD as she is, on her bad days of testing, still average for grade. On her good days -- wow! I don't know if I'll be much help as we've not figured out a way to fully address the spelling errors, headaches when reading, losing place on the page, poor written conventions. We've taken more a route of trying to accommodate and come up with ways for her to notice that she's making these errors.
She's in a very structured middle school, I'm going to work with her this summer if she'll let me on reading words in groups rather than word by word, she types whatever she can to make use of spell check, I review her writing and point out errors to her but leave it to her to figure out what the error is once I point out where it is, etc.
Good luck. Let us know how it goes and if we can help.
