Insight & Guidance, please!

Alas, I've been mom to Oz Lestat (male, neutered, 10 yrs old) for 8 yrs now.  Shortly after adopting him, he developed this skin condition, primary to his head - but it causes him to itch excessively where he practically is tearing out his fur.  Each time I bring him to the vet there's a new "theory" as to "why" & each time they give me meds that "do the trick" but how can there be so many causes & yet it still comes back?

I've been told:

• Low - White Blood Cell Count
• Fleas
• Ticks
• Stress
• Environmental Factors

A year to two or three years will pass between each flare-up.  And in my opinion, 90% of the time, the cause is generally around a potential "stressor" in his life.  In the past 3 weeks, I adopted a new kitten, suddenly, Oz is itching again - scratching away the fur around his head.  Fur's flying everywhere in the house - & he's utterly unsettled.  He's an indoor cat, though I know he longs to be indoor/outdoor.  We just don't live in an environment suitable for it (we're in a 'rural' city - living on a street w/maniac drivers too close to the road).

Of course, each time this occurs, I'm short on cash & need to "home" remedy him until I can stranglehold $300 for an office visit & medicine - but my question is - is this something anyone's ever experienced w/their cat or is my cat unique???

It seems like that stress is the cause of the breakouts.  Have you tried a Feliway diffuser, Rescue Remedy, or some of the things from Spirit Essences? 
 

how about leash training or a cat stroller?

what did the vet prescribe that cured it previously?