I agree that it is so frustrating when a capable child fails. Your idea of a tutor is a great one. Unfortunately, most tutors do cost money unless your school or county provides free or low cost services to their constituents. Give your school a call; usually the counseling dept. handles this kind of a question.
 
You might seek other opportunities too. Consider having a capable student in 8th grade or above work with your child --- under your supervision, of course. Usually a person can get another student at a fraction of the cost for an adult or another type of tutoring program.
 
If you can, take time to sit down and study with your child; two working together is usually more fun than just one. Another option is to have your child sit at the kitchen table and work on homework while you cook supper. Sometimes a child just needs a "buddy" around. That way you can keep an eye on your child's progress and be available to help answer questions "immediately" when questions arise. Consider too shorter but more frequent work sessions. For instance, when studying vocabulary, ask your child to study only the ones he doesn't know, and then review those for 5-10 min. for about 3-4 times a day. I suspect your chld will find that he learns these better by studying shorter periods. I also find it helpful to have the child work with a timer, especially on math homework. I always ask the child how many problems he think he can do in 5 minutes. Let your child set the timer and work against his set time. If he makes his goal, give him a pat on the back. If he doesn't make it, just encourage him to try again.
 
Good luck in coordinating the help your son needs. Ms. A