Girls, good night ? I wanted to ask you, we'll be three months in a we…

Girls, good night ? I wanted to ask you, we'll be three months in a week, and here today the baby started coughing with phlegm, is it normal at this age? What should I do? He sleeps and constantly coughs ? makes such sounds like he's suffocating, scary, I immediately pick him up, is that normal at this age? How to cope? When will it go away?