Is it my age?

When I started college in 1991, I was able to memorize pages and pages of information - word for word.  I could record it on my test and be accused of plagiarism because the instructor thought I had copied it from a page I was hiding.  Imagine being accused of cheating when I was only an overachiever.  I had to have the most points possible in the class.  I even would do the extra assignments to get the extra bonus points because I had to have an A in each course.  I wasn't even stressed over all of the work.  I loved the homework and assignments and all of the extra work.  It was like a drug and I was addicted.  Only the drug was getting top grades in class.  Now mind you I am not really a smart person.  I just study and make the passing grades.  After the test is over I usually forget everything I had learned about that particular subject.  I graduated cum laude with a Bachelor's degree in Education.  I had to ask what cum laude meant.  I graduated from college in 1996 and ever since I have been taking continuing education classes.  I am currently obtaining my master's in business administration.  And that my friends may have been the least smartest thing I have ever done.  Oh, not the masters. But getting it in business.  I am illiterate when it comes to math subjects.  No, let's just tell the truth.  I am ignorant when it comes to math.  Well, I have tried to memorize the terms.  I have tried to memorize the theory.  I have tried to do the math assignments.  This accounting class is harder than the business law class I took.  So, tonite is my final in accounting and I did not study like I should have.  I worked too many hours and have a dysfunctional marriage to contend with.  I am so tired and exhausted and the weather is so hot (108 degrees at midnite for days now) that my asthma is acting up.  I am afraid I am going to fail this accounting class.  If I do then I will be put on academic probation and the course will cost me an additional $2,000.00.  Very costly.  I feel like a failure.  Is it my age that I can't study and memorize like I used to?  My marriage was worse back when I started college and I graduated with honors.  I took a full load each semester and made top grades.  I am not bragging I am just explaining how things used to be.  Why am I failing? I know that master level classes are harder.  I know that being in graduate school is harder.  I just don't understand why I can't at least pass each course.  I don't need to have the highest grade anymore.  I just want to pass.  I don't want to cause my family anymore financial burden by having to pay an additional fee penalty for failing the class.  I want to graduate.  I don't expect to graduate with honor, but I do want to pass.  So, is it that I am 51 years old and my memory is not like it used to be?  Or did I take on too much?  I needed the challenge.  I needed a goal.  And I believe that getting my MBA is the right thing for me in my life right now.  I just am worried am I really getting old now?  My multi -tasking skills have done worn out.  I want to know is anyone else out there slowing down like I am?  I forget to take my vitamins and I am supposed to take them for my memory.  Oh, well, I guess I have postponed taking my final as long as I can now.  Here goes nothing...