The cold sweat was an indication of cardiac ischemia. Lack of oxygen to the heart. The light-headedness was due to reduction in cardiac output due to stimulation of the vagus nerve on the toilet. The nerve is located next to the anal sphincter. Your husband needs an immediate (read as of yesterday) cardiac and neurological evaluation. If it happens again you have a 911 call and he should be transported to the hospital by ambulance.
Ofcourse the condition is more common in the 50+age group.
Surely yes, because prognosis is very favourable in the younger - TIA with therapy, if spotted and treated at the earliest.
For all that you know this may not be TIA,yet it is better to be aware.Do consult your doc.
Best wishes.
He is 30, if that indeed does make a difference.
If your husband is beyond 50 he must get examined to rule out TIA(Transient Ischaemic Attack).