Bob Ewell claims in his trial testimony that he saw Tom Robinson assaulting Mayella through a window, ran around the house, and that Tom Robinson ran out the front door before Ewell could get to him. Then, he claims, "I was too distracted about Mayella to run after 'im. I run in the house and she was lyin' in the floor squallin'--" Apparently, Ewell didn't stay distracted for long, however, because he states that he then ran to get Sheriff Tate; Atticus asks him on cross-examination if he ever thought, with all this running around taking place, to perhaps run and get Mayella a doctor, but Ewell responds that it would have been too expensive.
On the witness stand, Bob Ewell states that although he witnessed the assault by Tom Robinson upon his daughter, he did not run after her attacker because he was too disturbed about Mayella to think about running after Robinson.
Curiously, although Ewell claims to have been "too distracted by Mayella's condition" to run after a fleeing Tom Robinson, he is not too distracted in his thoughts to immediately run for Sheriff Tate. Nor is he so worried about Mayella's "condition" that he goes for a doctor. Ewell's explanation for not having summoned a physician is that he has "never called a doctor to any of his'n in his life." And if he had, he would have had to pay five dollars, Ewell adds.
Without realizing it, Bob Ewell says things that suggest his statements are not forthright. Were he truly concerned about Mayella, his thoughts would have been singularly on his daughter's safety and health; therefore, he certainly would not have left her alone with her right eye blackened and potential internal injury to run for the sheriff rather than a physician. Nor would he have been concerned about the cost of the physician at that time. During his questioning, Atticus cleverly reiterates to Bob Ewell all the times he ran in order to emphasize the inconsistency in Ewell's behavior of not running for a doctor. By doing this, Atticus hopes the jurors will find Ewell's testimony dubious.
He said that Tom ran out the door and he did not have time to chase after him since Mayella was in pain. However he soon ran to Sheriff Tate and told him about mayella. Atticus asked if he asked to see a doctor but Bob said that would have been too expensive, and here we know Bob hit Mayella.