Hello again,
The mood stabilizer and antibiotic are important as some combinations may prolong the QTc (part of the heart's electrical cycle) and this can cause the symptoms you are describing and if reviewed by someone not familiar with the differences in kids vs adult EKGs can go unnoticed and cause major problems if not addressed. If he's on Biaxin or Zithromax as an antibiotic and haldol or Geodon as a mood stabilizer, stop the antibiotics and call his doctor.

If not, there are a few things that can cause his problems. Certainly the ongoing sore throat and fatigue can be linked to a prolonged viral illness (like mono). The constant sniffing certainly sounds like an allergy issue, but should not be related to anything but possible the sore throat and stomach ache (from post-nasal drainage) and shouldn't cause passing out.

Some other antibiotic/mood stabilizer combos can also cause liver problems, so watch for easy bruising or yellowing of the skin/eyes.

Check his medications first and foremost for any of the dangerous combos that need to be stopped ASAP and then go from there.

Thanks for the question, and I hope this helps!