Lawyer here. The above is pretty good advice. I would NOT recommend using law as a backup. I myself decided on law as the best of the options available to me after undergraduate school. I have practiced law for 15+ years now (in litigation) with some reasonable success. Being a lawyer has its good and not so good points, but I've felt for some time that it's not the best fit for me--hence my interest in medicine.
My advice to the OP: if medicine is what you truly want to do, find a way to do it. Apply again to US MD/DO, and if you don't get in, try the "big 4" Caribbean schools (St. George's, American University of the Caribbean, Ross, and Saba). Life is too short to do what you don't want to do.
So I'm a long-time lurker and a rare poster, but I feel like I can chime in here, based on my experiences. I agree completely with FutureBoy. I'm a full-time attorney, and I'm trying to change careers to medicine (I miss science, among other reasons).
I can say, without a doubt, that you shouldn't "settle" for law, if medicine is what you want to do. Though both field rely on similar skills (analysis, critical thinking, etc.), the two are entirely different beasts. I do not mean to disparage the legal field - it is challenging and has its rewards, but it is no substitute for helping someone become healthy, etc., if that's what you're interested in. On the other hand, if you're interested in health policy, a legal degree might be a great way to break into that field.
In addition, other posters have claimed you need a particular undergrad background to get into law school. Not true. You merely need a decent LSAT score.
As for the lawyer salary discussions - it all depends on what field you enter, and somewhat where you go to school. Public interest work (public defenders, legal aid, etc.) doesn't make much, but is perhaps a more satisfying field. Civil litigation jobs (patents, torts, etc.) can pay much more, but often have higher rates of dissatisfaction. From what I've seen, the legal field is very enamored with rankings and standings. So you're more likely to get the job you want if you went to a top 20 or top 10 lawschool.
Anyway, I hope this wall of text was somehow helpful and not too preachy. Good luck to you all in getting either into medschool or whatever other field.