Ds2 (6) has been getting more and more run-down and depleted over the past couple of months.
He has had problems with constipation recently (for which he is on movicol) that developed after a series of d&v viruses at the beginning of the autumn term and I know the constipation makes him feel poorly, but this is something entirely different as far as I can tell.
He very pale and has dark circles under his eyes, gets regular cramps in his feet and calves and seems to just suddenly drop into a sort of total exhaustion where he just wants to lie down and close his eyes. He does still play, but not as often and regularly refuses to play with his brother because he's too tired or just wants to lie down.
Other than the bowel thing and the cramps, he has no specific symptoms, but is obviously unwell. He is usually such a happy, smiley, lively boy and he's barely recognisable at the moment. 
In addition, we've noticed his cognitive function is becoming impaired. He is struggling to do school work that ordinarily he would have breezed through. The other day we were doing homework and I asked him what four minus one was and he couldn't do it, he just stared at me blankly, said I don't know and burst into tears.
I jollied him along and reassured him and he did do it, but only by working it out on his fingers. He is having similar problems across the board with reading and spelling, almost as if he has some sort of mental confusion or brain fog.
Worst of all, he is aware that this is happening and is starting to label himself as stupid as a result. We've had lots of tears about how he is struggling in school every single day and just can't do the work. I've tried reassuring him that he's just a bit tired and it doesn't matter if he gets things wrong, as long as he's tried his best, but its not helping.
I have spoken with his teachers and they have noticed the same things happening at school and also that his achievement levels are dropping. They did try doing some confidence building work with him and have done lots of work on encouragement and praise, but its had no effect. They are also very concerned about him.
Back in November, at parents' evening, we were told he was doing really well, looking at moving up into the top group for numeracy and literacy and they had no concerns about him whatsoever, so this has all happened since then. Thinking back, it has probably been a slow decline, that we only really noticed when it started to get more severe. I think we probably put some of it down to end of term tiredness and Christmas at the end of last year.
I took him to the GP yesterday and they sent him straight to the hospital for a range of blood tests. Poor little soul, they couldn't find a vein in either arm and he ended up like a pincushion he had so many holes in his arms and to add insult to injury, the LA cream had worn off by the time they managed to get any blood out of him.
He was so brave, especially as he is needle phobic already after a stint in hospital when he was seriously ill at the age of 4.
We have been through a similar thing with him once before, although that time there was an obvious cause. After being dangerously ill and hospitalised with pneumonia, he regressed emotionally and lost pretty much all the academic skills he had, having to start again from scratch learning letters and numbers etc at the age of 5. He was given additional support for a year and worked really hard to catch up to the point that he no longer needed additional support by the start of the summer term of year 1 and the only reason they didn't put him into the top groups for everything at the beginning of year 2, was that they didn't want to overface him and felt he would benefit from a term at the top of the middle group before moving him up. It feels like he is almost back at square one now though, being unable to do even basic sums and spellings, that he had no problem with this time last year.
The GP said if nothing shows up on the bloods it might be appropriate to refer him to CAMHS, as it could be psychological. Obviously I will do whatever it takes to help him get through this, but it just doesn't seem primarily psychological to me - he is so weak, pale and visibly ill.
Has anyone had any experience of anything similar. Obviously we are worried sick about him. The blood results aren't due for 5 days and other than possibly anaemia, I can't for the life of me think what could be wrong with him.
The bloods were for liver, kidneys, FBC, ESR and a coeliac screen (his brother has recently had a negative coeliac screen, but was advised to remain gluten free anyway due to obvious physical effects of eating wheat).
TIA