**
1. feeling pleasant before passing out can be attributed to fatigue but for one day only and thus could be due to ADR [adverse drug reaction] of claritin [loratidine] and allegra [fexofenadine] both of them causes
drowsiness and
dizziness [antihistamines]
2. If you have started to experience these symptoms, you need to lie down as soon as possible, so as to avoiding hurting yourself and others. [Drink enough fluids]
3. as you were diagnosed with
sleep apnea, possibly you are suffering from ISP [isolated sleep paralysiss] as duration is of minutes. [ and insomnia and
sleep deprivation are associated with increase risk].
4. many factors which increase risk can be avoided with minor lifestyle changes i.e. by maintaining a regular sleep schedule or seeing a trained
psychologist who can suggest coping mechanisms for stress
5. since you have three separate diseases, but one thing common in them is that they all are "PSYCHOSOMATIC" disorder which mean that unless treatment of mind is not done, physical symptoms cannot be cured [see also for Generalized Anxiety Disorder].
PS
i.
shallow breathing is one detrimental factor in sleep apnea and can be the cause of 'pass out'
ii. any amount of sleep deprivation will diminish mental performance, [One of the most common methods used to diagnose is a sleep study, which may require an overnight stay at a sleep center and will monitors a variety of functions during sleep including sleep state,eye movement,muscle activity,
heart rate,respiratory effort,airflow,and blood oxygen levels.