How do you tell if baby has a cold?

Probably a dumb question but I’m a FTM and I think my baby might have a cold. We don’t go anywhere so he rarely ever leaves the house (6 months old) but the last couple of days he’s been sneezing and coughing more and has a little runny nose. He doesn’t seem fussy or overly tired and no fever. What do you think?

I plan to call the pediatrician if it continues but I’m thinking they can’t do much about a cold.