Can you tell if it's muscular pain or is it joint/tendon? If it's muscular, then it's the pushups that are doing it. If it's joint or tendon, pushups may still be responsible but it could also be the pullups. I've had elbow pain from pullups when I didn't control my descent and just dropped into a dead hang. If you're doing this, then you may have aggravated the tendons attaching the tricep to your elbow. Only a doc or physio will be able to tell you for sure. Be sure to check your form on both pushups and pullups, and don't let things get too sloppy.