I would start with getting a second opinion. 1) you didn't like the Dr. to begin with and 2) As commin as it is, asthma is nothing to mess around with.
Next, keep an open mind about the meds. If a second opinion recommends them, then go with it. I have 2 friends who have had young children with asthma and have both had to go on the daily nebulizer treatments. The one has been doing them for about 1 1/2 years and has been able to cut back to just during cold and flu season. The other is a bit older and has basically grown out of the need for daily inhaler treatments.From what I've been told, these are low dose steroids, but keeps the asthma in check. These treatments are especially necessary during cold and flu season, when they are most likely to have a flare-up of the asthma.
I understand hating to have your child on any kind of medication long-term (especially something like steroids). But as much as you fear the damage any steroids may be doing to your son, imagine the damage that's being done to his body by not being able to breathe properly.
I also speak from experience of having asthma myself for the last 7 years. It is terrifying to have an attack (which only exacerbates the attack). And even as adult, I've many times underestimated the severity of my attack (having found this out after ER staff asked why I waited so long to get to the ER). A 2 year old has no way of telling you the severity of his breathing problems and you may not know until he is in a full-blown attack. The meds will help prevent this from ever happening.
As far as figuring out the source, I would see an allergist and have him tested to figure out what if he has any allergen triggers. These could be environment, diet, weather, etc.
Here are some things I have learned as a lifelong allergy and adult asthma sufferer:
If it is allergy triggered you can help elminate triggers by:
1) Keeping you home as dust free as possible. dust and dustmites are one of the biggest triggers out there.
2) Buy hypoallergenic pillow, mattress and comforter cover.
3) Use blinds instead of drapes.
4) Hard floors instead of carpets.
5) When cleaning with strong chemicals, have him out of the house (or away from where you are cleaning).
6) No pets that shed or have dander (there are some dogs that do not have this issue and don't bother allergy sufferers - ask your dr.).
7) Use fragrance-free, hypoallergenic, soaps, shampoos, lotions and laundry detergents.
8) No smoking around the child or in the house.
9) During high pollen season (you can find the pollen rate in your area on www.pollen.com) keep the A/C on.
10) Try to avoid overheating in the summer and in the winter, try to stay warm.
11) If you have mold or mildew get it cleaned up asap. These are also major triggers for many people.
I know firsthand, how difficult it can be to live with asthma. But if gotten under control your son can have a perfectly normal, healthy childhood. In the past, I have made several trips to the ER b/c of asthma attacks, but with the help of low doses of medication and following some of the suggestions above , I really don't have a problem with it very often anymore. I am basically off of the medication (with the exception of the rescue inhaler when I flare-up), I excercise, Ikept my cat, and I live in excrutiatinglu hot S. FL. all without any attacks for nearly 2 years.
I hope this helps. Good luck.