URGENT: Need help with Question

I have a multiple choice question with a Submit and Next button on the page. And i am manually calculating the score on Submit button action based on the leaner's choice. Now the problem is the learner Submits the correct answer and the score is incremented by one and quits the course (without clicking the Next button). Next time when the learner resumes the course, the learner will be brought back to the same question and there he can answer the same question again. If the learner selects the correct answer again, the score will again incremented by one. This brings down the whole assessment result.

If anyone has a suggestion, please let me know.

Thanks in advance,