It's cold and I have a cold.

It all started a couple of weeks ago. First, I had a sore throat and felt a chill. I went to a chemist and bought a medicine for colds. After taking the medcine for a few days, I felt much better, but then my husband became ill. He said that he caught a cold from me, so I gave him my medicine. A few days later, while my husband got better, I started coughing. My husband said that that's because I stopped taking the medicine before my full recovery. We both took the medicine for a few days and finished the pack. During the next few days, we were both well, and even went to the gym to do some exercises. However, my husband came back home very late last Saturday when it snowed and was very cold. He started coughing and seemed ill. He went to the chemist on the next day and started takig the cold medicine again. And, guess what? Since this morning, I have a sore throat. Boy..., when can we get out of this negative spiral?