Hi Serene,
I went back to look at other thread (hadn't seen it) and think the OP is very different in it's concerns (real or pretend) to yours. Which are obviously real, and heartfelt.
I don't think anyone who is joking on the other thread would dream of joking about your post: level 2s in Y4 are understandably worrying, whereas level 4s are definitely not.
I wish I had some practical suggestions for you....I am sure others will, so am bumping post for you. What I do know is that there is a fantastic lad in dd1's Y4 class who has been struggling for several years, and it is heartbreaking. 'Not bad enough to be statemented' makes my blood boil 
as I'm sure it does yours.
Thankfully, dd's friend finally got a diagnosis of dyslexia and on the second attempt he got his statement. He had to be two years behind, I think, in order to qualify - which is utter madness, but apparently is how funding works.
I also have a friend with a younger (8) dd who is very bright but struggles with attention span. Practical tips she was given included working for a few minutes per day, one to one, with her - and seating her dd on a chair it was harder to slide off/wriggle out of. One with arms, for example, or high up. Also, to send her to run around the garden twice before sitting down to read/concentrate on anything. If that helps, you can ask the school to try and get ds to do a few star jumps, a quick run, anything physical that helps contain his energy before he sits down to learn.
She has also tried giving her dd something 'allowed' to fidget with whilst listening - eg play putty/playdough, or a squishy little ball.
Wishing you the best, and hope others come along with more practical ideas for you.