Results published by others first in parallel. Is my work still publishable?
Get personalized advice from a professor at your college. It sounds like your current problem is not publishable anymore since you've been preempted. Still, there could be a way to spin it so that it's still publishable (the fact that you're using it in a different field is a good sign), and if so a professor at your college who can examine the problem and the proof firsthand is the best-positioned person to help.