is my son still contagious?

It's Sunday so I can't ask his doctor. But my son has had what I believe to be a cold for over a week now (doctor said allergies)but I personally think cold but I'm not the doc so I don't know. His symptoms are just a runny nose and a dry consitent cough. he hasn't ran a fever or anything like that thankfully . I know it's contagious but online says 5-7 days they are contagious. I have a newborn at home and it's heartbreaking and so hard to keep my son away from his new sister and spraying enough Lysol to last a year and i don't know how long I can and have to keep doing this.