This happened to me. Took CS and discrete maths in my 3rd year of premed. Final year I did some computational neuroscience research but with basic Python stuff. Went to grad school to study computer engineering and taught myself CS along the way.

I would avoid the 2nd BS. It's a bad ROI for time and money. An MS is also a delicate choice and you should only do it if your program caters to students with a non-traditional or non-engineering background. This way, you'll have the chance to take foundational courses. An MS is expensive but it's still cheaper than a BS.

I got into my MS program due to high GRE scores and high grades in the CS courses.

A bootcamp is also an option, but choose one that covers the fundamentals thoroughly.

You can apply to jobs while self-studying but it will be harder. Without strong projects or extracurriculars (e.g. hackathons, clubs, open source), there is a low chance your resume would get through.

However, if you can find a job where you can use your strengths in Biophysics and CS, this is by far the best option.