I, like you, try to avoid medicines for all of us, unless it's really necessary. To strengthen the immune system, try elderberry syrup--it has completely kicked 95% of the sickness in our house, and has really lessened the severity of the other 5% of illnesses. Take it at the first sign of sickness--even babies can take it. For my kids, I either use a liquid syringe (like the one that's used to measure most kids' medicines) or I use the syrup to make a "juice," diluting it with water.
These past few weeks, we were all sick at one time or another, and I didn't stay on top of it all very well. So I got a nasty cold. My mom told me to try Umcka--it is wonderful stuff. Again, a natural remedy, and even kids can take it. You take small amounts of the liquid several times a day until your symptoms subside--by the third "dose" I had noticed a huge change in my congestion, cough, and just the way I felt.
Try these things, they really do work. I feel like I'm still learning about natural remedies, but I'm so thankful to have discovered these two. Be well!