Ask if you can work in the lab you are working in now! You need continuity. If you can't get into research, try to get a summer job - medical schools appreciate people who understand the value of hard work for pay. You can show leadership at your place of work.
Honestly, I would be cautious of setting your sights on MD/PhD, you will have a tough road ahead. I get the issues that you are describing, but the fact is that there are many students out there who will have more luck than you. Students who get a chance to work on their own project, students who will have posters, abstracts, presentations, publications, a thesis, a higher GPA, better ECs. I spent all my time in research (20+ hours a week plus a part time job all 4 years of college) so I get how hard/impossible it is to get meaningful ECs that you are excited about with that kind of load. Unfortunately for both of us, there are superstars out there who will do all that and more.
Applying this cycle has been a great humbling experience for me, don't let research accomplishments lull you into a sense of security - you need those EC because you can't count on an MD/PhD
Note, I did not apply MD/PhD but I can tell you right away that your competition, especially at the top research schools, is really really stiff.