Others have given great advice. I agree with the recommendations that you should look into getting a full nueropsych eval.
Sometimes individuals with SPD have other processing difficulties, such as Auditory Processing Disorder or visual processing problems. APD can look a lot like ADHD and is often misdiagnosed as such. APD testing needs to be done by a specially trained audiologist and the testing can be done as young as 7 years old, so that's something to keep in the back of your mind for the future.
Anxiety can be a big issue for people with SPD and/or other processing issues. And that's understandable, because when the information you get from your senses doesn't make sense, the world can be a really scary place.
Hugs to you and Greenbean. It can take a long time to find answers and often a diagnosis evolves over time as a child grows.
Gena
DS, age 11 and always amazing
“Autistics are the ultimate square pegs, and the problem with pounding a square peg into a round hole is not that the hammering is hard work. It's that you're destroying the peg." - Paul Collins, Not Even Wrong