How to get into alternative medical school caribbean/abroad for US students?

"Alternative medicine" is superstitious quackery.

If by "alternative" medicine" you mean the legitimate schools of Medicine in the Caribbean, be aware that your GPA puts you at serious risk of failing.

If you have a low GPA for Med School, you may not be a candidate for PA school, either.

Once you take your MCAT, if you want to practice Medicine in the US your two best bets are to attend a Caribbean Med School (there are several) or UAG Med School in Mexico (in their international program, not their latino program). Those schools are seen as legitimate Med Schools by US Residency programs, and have much higher acceptance rates than any other international Med Schools. These schools still don't match at as high a rate as traditional Med Schools (especially not in surgical or specialty residencies), but almost all their students match to a primary care Residency (Family Medicine, Pediatrics, Internal Medicine) within 1 year of graduation, as opposed to a 5 year timeframe for other international schools.

To attend one of these schools, just apply as you normally would for Med School. These schools still have an average GPA of higher than 3.0, so if your GPA is lower than that, you'll really have to excel on the MCAT.

You mention that you are able to do higher level science courses, but still don't have a good GPA. If any of your issues with maintaining a high GPA have to do with reading, writing, or test-taking, find a tutor NOW to help with those things. You will be doing a LOT of reading in Med School, all of your course grades are based on exams, and you'll be expected to do some research and academic writing in preparation for your Residency program.