C.L.
I have a 15-year-old who was diagnosed with asthma at age 2 and a 12-year-old who developed "reactive airways" after having RSV at age 4 1/2 months. The wheezing and frequent colds your son has been getting could be asthma, reactive airways or just frequent colds and he's subject to the wheezing because he's still recovering from the RSV. It's probably too soon to know. Reactive airways fall short of asthma, but basically means that someone's airways react more than is typical to colds and upper respiratory infections. My son would develop a severe croupy cough that came on suddenly with a cold. A couple of days of frequent nebs usually took care of it.
If your son is better and the wheezing and congestion are better it's probably fine to stop the nebs, but I would at least call the doctor and not wait until your son's next routine appt. If your son continues to have problems another option is to talk to the doctor about a medication that prevents and treats the inflammation and isn't a "rescue med" like the albuterol in the neb. Usually it's a steroid. A "burst" of oral steroids (usually 3-5 days), not suited for long time use because of the side effects, can be helpful for inflammation. Did he have any during the initial virus? We only used them when my sons were so inflammed that coughing prevented them from sleeping at night or their blood oxygen levels were down. Inhaled steroids help the inflammation because they go directly to the airways, but don't cause the side effects because they don't get into the system like oral steroids.
As for the nebs, I know I hard it can be to get a toddler to sit still for them. We used to let our boys watch their favorite or special videos for the neb. Thomas the Tank Engine was popular. We even had a video called "Baby Breaths" that was specially designed for this purpose and had special calming music and showed footage of babies and toddlers taking their nebs. We also read books during the nebs and had a book designed for this purpose called, "The Lion who had Asthma." It depicted a little boy who used his imaginiation during his nebs and sometimes pretended to be an airline pilot or a roaring lion while he nebbed. If he has a mask for the neb he can also play quietly with blocks, toy trains, etc. while he nebs.
It can take a long time to fully recover from RSV, depending on how severe it was initially. He could be just more prone to the colds and viruses because he's still compromised. I would keep in touch with his doctor and monitor his symptoms. Our pediatrician welcomes phone calls. It's a good idea that you cancelled playdates with friends who have colds now. Good luck.