2 month old, wet cough, congested nose, more fussy and crying, flemm comes out mouth, had his tdap vaccine already, what could this be?

Rhinovirus: your pediatrician needs to know. With any history of fever they also will want to see home/her. Rhino virus is a common virus but a 2 month old they will need a call. Hope this helps

Infections: such as RSV or influenza can case the symptoms you have described. Very young infants do not handle infection well, so prompt medical evaluation is warranted.

URI: your child has an upper respiratory infection. He has a running nose with a post nasal drip causing his cough. The mucus from his nose may have gotten into his ears causing his crying and fussiness. Use salt water nose drops and a vaporizer to help his cold symptoms. If his crying and fussiness persists have his pediatician check his ears.