baby cough

My baby just got off antibiotics about 4 days ago due to him having sinus infection & today he woke up with a dry cough & his throats sounds raspy, his temp is 99.5 rn. He has his 6 month checkup this Wednesday. He's not coughing constantly but I'm worried now that it could be something more serious should I take him to ER rn or should I wait if he gets a fever or go in make an app tomorrow with his pediatrician or wait it out until Wednesday? Is there anything I should do? Ftm I'm scared my bf says to wait but omg idk