10 y.o. like 'drunken sailor'; doesn't eat

Our son is nearly 10. For three years now he has been taking medication to control fits. This is after an initial grand mal that alerted us to his problem. An EEG showed that he was having almost continous absence seizures and petit mals. The specialist started him on Epilim. This reduced his apparent fits most considerably. He would still do a 'monster act' regularly, shortly after awaking each morning and maybe once or twice more during each day. During such fits his arms would raise involuntarily and his eyes roll back so you could only see the whites and he'd make a strange involuntary noise. Of course, if he was holding anything like a drink, this would end up everywhere. He would also wet himself if his bladder was full. Adding Lamictal to the daily med regime has cut back again on the frequency of the visibly obvious fits described above so that they are now quite rare. Prior to being diagnosed, Tak (as we will call him here) seemed to be developing cognitively quite well. In fact as a pre-schooler (aged 3-5), he had taught himself to read with little or no help from his parents. He seemed in those days to be prodigiously intelligent. I sometimes wonder now if the brain lessions (or whatever is the cause of his epilepsy) resulted from very quick early brain development. Just prior to his first fit we had become concerned that he had a speech impediment because he would repeat phrases and not complete sentences. The reason why is now clear to us. The drugs seem also to have helped this aspect of his communication. Though it is still a little slow and disjointed, he can verbalise with more confidence. Increasingly though now it seems that he does not even try to express complex thoughts. His teacher has been very patient and understanding. He can see that the boy has basic intelligence. But of late even this teacher's patience has been tried to the limit as Tak's ability to stay focussed and on topic seems to be slipping away, so that now he doesn't even try. He seems always away in 'dodoland". I guess that we should be thank goodfull that he is not naughty or energetic! Tak's father has been keen to have him partake in sport. The junior levels of soccer are uncompetitive and once again the school and the coach and the team mates have been supportive. Still, it has been frustrating to see the other boys' motor skills developing while Tak, if anything seems to be regressing in this regard. Just lately, with any physical activity he looks like a drunken sailor who hasn't any land legs. He wears out very quickly. Tak seems to require lots and lots of sleep. He will often fall deeply asleep during the day - even at school. Lately he has been in a very long spell of not eating much at all. This loss of appetite means that he nibbles at food, eating like a sparrow, never finishing enough even to feed a sparrow. I am writing now because I'm trying to work out whether the most recent slippages in his mental and physical capabilities may be a result of lack of nutrition compounding the symptoms of his illness, or whether, the problems I describe (lack of concentration, sleepiness, dizzy behaviour, lack of appetite) may all to some degree be drug side-effects? Possibly there is someone with similar experiences who can offer an opinion, thanks? Our specialist is away on extended leave. We are worrying that if Tak doesn't eat soon he'll waste away to nothing.