That is an extremely high dose of DOC, it's not suprising that your brother is feeling out of sorts. However, I would not be so hasty as to go to the doctor yet. Firstly, most doctors have no conception about psychedelic matters, they are as ignorant as it comes. They are far too prescription-happy, and the last thing your brother needs is to end up on some dreadful "medication" for something that time will heal, or end up getting sucked in to the revolving door of psychiatric "care" (the 21st century dungeons of hell). As strange as it might sound, you are far more likely to get proper advice from an informed community like bluelight, who know what they are talking about through experience.
If your brother is feeling dizzy, spaced out, or having brain zaps, it would point to simple serotonin or catecholamine depletion, causing 'norepinephrine whiplash' (especially at night when trying to fall asleep). This is easily remedied by eating well (lots of wholesome foods, salads, nuts, pulses, legumes, fruits etc.), getting lots of rest, and some physical excersise (a bit of cardio in the morning or whatever). In a week he should be feeling right as rain physiologically.
The psychological scars of an intense ego-shredding experience may take longer to intergrate and figure out, however it doesn't sound from your description like that's what he experienced. It sounds more to me that he just got in to a zone of intense overstimulation for many hours, and now he is a bit "burnt out".
If needs be, it might be worth him supplementing with 5-HTP for a week or so, until stores are back to normal. Eating well, including lots of amino acids and vitamins, should sort out the rest.
But again, I would highly advise against going to a psychiatrist for this. It will only make things worse in my opinion. In general, psychiatrists and general practitioners really have no idea what they are talking about when it comes to these things. I'm sure there are a few who do, but they are few. Most of them just parrot what they are told by drug reps. And because of that, your brother is actually best off doing some research and taking care of himself.
Now he has had his butt spanked by his own stupidity, he must make sure not to be such an ignoramus in the future. That includes thoroughly researching every compound that he wishes to ingest, and going about it in a responsible manner of care for himself and others. This advice applies to everyone who may do the same.
