It depends on what you're nebulizing as to what the medication is supposed to do, but assuming that you're nebulizing albuterol as many of us do, the point is to open up the airways to make breathing and coughing up mucus a lot easier. My question to you is did the nebulizer treatment work? If it did, and your rescue inhaler seemed to have no effect, the the nebulizer did its job just fine. The inhaler didn't work because the nebulizer already had done it and was still working.

You don't say what medications you have been prescribed with the nebulizer but in general the particles are made smaller and can be inhaled deeper to provide nore relief. Unfortunately the strength is lower and wears off quickly: within 4 - 6 hours. Repeat treatments are required due to this alone.

Conversely the single dose inhalers (powdered or misted) are lager particles (aka stronger) but are often trapped in the throat and bronchial tube if not inhaled correctly. But they are designed to control our respiratory conditions for longer time periods if not the majority of the day.

In your case, taking those two different medications in close proximity to each other would likely result in reduced action based on the type of meds you have. My nebulizer treatments are spread throughout the day and at least two hours from the main inhaler dose (before or after).