Sentence 1: Tom's wrists had been hurting recently. 
 Sentence 3: Tom ordered a brand new mechanical keyboard online 
 Sentence 4:  It came in the mail the next day 
 Sentence 5:  Tom's wrists no longer hurt with his more ergonomic keyboard 
 Option 1: It was due to his cheap mouse at work. 
 Option 2: It was due to his poor keyboard ergonomics at work.