How did i catch a cold?

yesterday i helped a client who was sick. i could tell she was sick because she had the "sniffles" and asked me for some kleenex tissue. today i woke up with a runny nose and was sneezing a lot. recently though, we've had climate change. so the weather has been alternating between warm and cold a lot. do you think i got sick from my client or from the change in weather? i just find it crazy that i would get sick so fast from another person. and i rarely get sick too.