Medical schools usually pay no attention to letters from private counselors. Your letters will have to come from your college faculty. Dr. Lewis knows that. However, Dr. Lewis was a well known, successful and respected advisor at one of the California universities. That MAY carry some weight. And of course she earns her living from making use of her expertise, the same way a physician earns her living by making use of her expertise. How many people do any of you know who use their skills without expecting recompense? As a physician, will any of you set up shop and not charge a pretty dollar for the use of YOUR professional skills?
Whether you have to or should use a professional advisor, I cannot tell you. If you have an advisor, use that advisor. If you are at a college without an advisor, you may want to consider paying for a private one. Without knowing any details about your situation, I cannot say what you should do.
There is another alternative, although it does not serve as a complete substitute for an advisor at your college. Some, but not all, medical schools are willing to give some counseling advice on a one-time basis. Call Admissions at one or two medical schools in your area and request what is commonly called a "counseling" interview. That usually consists of basic advice on course work and a few other things a premedical student must know and do.
But then, the responsibility of knowing what to do and how to do it is yours.
Permit me a question. Imagine yourself now a physician in practice. You discover that several of your patients are seeking medical advice from friends, neighbors, a pharmacist, a self-help medical book, a website (analogous to this) where non-physicians, of whom nothing is known about their skills, offer medical advice based on their personal experience. "My son had something like what your're describing. This is what I did, and see, he go well. Try it!" What would be your reaction, Doctor?
Live dangerously? See a physician?
Premedical advisors are "doctors". Of preprofessional advising, that is. And while they do not attend Premedical Advising Schools they learn their trade on the job and through networking with other advisors, professional schools, professional meetings, feedback, experience, a professional list-serve. But like all professionals--physicians, lawyers, electricians, stock brokers, musicians, etc.-- some are more skilled than others; some are more personable than others; some are better listeners than others; some are wedded to their profession, others are not; some watch the clock, others don't; some care, others not.
And some work under better conditions than others so they can be of more help to students.
Look both ways before you cross the street.
Finally, one of my favorite aphorisms, from an old Walt Kelly comic strip 'possum living in the Everglades--Pogo by name.
"We has met the enemy and he is us."