First thing first. My prayers go out to you and your family. This is a very challenging situation. My daughter started around 18 mos and continued until 7. (3 to 4 x a day, depending on her health). It is not easy, but it has to be done. The crazy part of it is that she now looks fondly at her time when we played "dinosaur", her favorite mask looked like a dinosaur and the mist looked like smoke to her.
Think of this time as an opportunity that most people do not get. You have several times a day where you get to just snuggle, sing, read, watch tv etc with your little guy. Kids can read your emotions and anxiety. If you act like it is a special time, soon you will realize that it is. Your baby needs this medicine and like all babies, he need you. Have your husband take the evening treatments as his opportunity to be with your son alone. Eventually your baby will be able to be left alone while he reads or what ever on his own. You will miss the time where you can just hold him. We all try to multi-task, but truly try to do nothing but be with you son during his treatments. This will relieve plenty of the fight, who doesn't want to snuggle with mom, dad or care giver.
Also, I removed all toxins, pertoleum, etc. from everyday cleaners, detergents and such from my home. I know it helped in the long run. I use nothing, to this day, but Melaluca products. There are now many alternatives found even in most grocery stores. They may seem expensive, but actually are way less expensive because they are so concentrated. If you want more info, feel free to contact me.
Best of luck to you and do not give up! You can do this (and alot more) than you are aware.