Croup or asthma?

Ok, I've seen so many doctors and specialists, I'm going to give you guys some input here, cause no one else knows!
Every time the weather changes, my son gets a bad cough and wheezing. When he was younger, it sounded croupy and barky, but now it's more phlegmy. He's in pain when he coughs, his throat hurts, but has no signs of his rib cage pulling in (usually an asthma symptom). But at times, his breathing problems make it almost impossible to wake him and he goes "limp", and that's when we have to take him to get treatment. He rarely has blue lips, but it's happened on occasion. When he's fully awake, he's much better. He responds well to steriod treatments.
He's fine during the day, it's only at night, lasting two nights five months out of the year (Sept, Nov, Jan, March, May, August sometimes). It's kind of predictable that way.
He has no problems with exercize and exertion, and runs and plays normally.

He's 4, too young for an asthma test. He takes albuterol (two puffs last night, only during an attack), and he got worse a half hour after that, while sleeping. Liquid steriods work well over the two nights, and we tried Flovent (long-term med. for asthma), but it hurt his throat and made him cough a lot, so we had to stop it. (He was better without)

I am the same way and have been my whole life. I get that way at night, when the seasons change. I was told by my specialist that when the seasons change, it affects my allergies & hay fever that causes my sinuses to run and drain down my throat. Which in turn, gives me bronchitis and makes my airways spasm causing me to have an asthma attack. I have to sleep kind-of elevated and on my side or stomach to lessen the symptoms. Sometimes I even sleep with a humidifier to keep the air moist so my throat doesnt hurt when I wake up. I would say take him to a specialist, like an allergist or an ear, nose & throat md to get him tested for allergies and hay-fever. He may developed some allergies recently that triggers his attacks. Also ask your md about Singulair, they have chewables for his age. It helps stop those "triggers" from affecting him.
I hope he feels better :)