You practice too often and have no rest. A large muscle group like the pectoral muscle needs 1-2 days of rest and recovery time, depending on your physical recovery ability and training volume.

Besides, just practicing your chest muscles is not good for you. You must also pay attention to the training of back muscles. The uneven development of muscles in the front and back of the body makes it easy for the pectoral muscles to pull the shoulders forward, which is ugly and bad for the joints. I used to only practice my chest, but now it hurts to lift my arm back and push it hard.