A few other suggestions would be to boost up his immunity by taking vitamins and probiotics yourself so he can get them through your breast milk. Florify probiotics are great supplements and VERY affordable, compared to others on the market.
Also, I am a BIG proponent of chiropractic adjustments for everyone, including infants. I have been seeing a chiropractor for years and totally believe in the benefits of chiropractic care. I got adjusted during both my pregnancies and my children have been adjusted since they were days old. We have given our chiropractor the title of our primary family physician and we see him before we go to the medical doctors (that’s how much we respect his expertise!). If you go this route, be sure that you see a pediatric specialty chiropractor for your son…there are chiropractors that will adjust infants and children without specialized training and it may not be a good experience.
Finally, when my girls get congested I rub them down with essential oils, R.C. and Raven. I order mine online through Young Living, but I’m sure you can find them at natural food stores. The oils usually help clear out their sinuses and get the gunk out. It doesn’t treat the infection, but keeps them more comfortable. I use the oils all over their hair, clothes, bed sheets, blankets (avoid the eyes) etc. and reapply 3-4 times a day until their symptoms clear.