I'm desperate. I NEED to do something this summer (post-junior year) that will help my application

I've applied to at least three highly competitive programs and have gotten rejected all of them. I really want to do something that will enrich my experience as a student working towards the medical field. For reference, I'm interested in biomedical engineering and dermatology. I'll take a CNA class next year in the spring through my high school. I plan on volunteering at my local hospital every chance I get.