My son is finding himself in a similar situation. He has a Physics degree but didn't get into postgrad school, or at least not the particular program he wanted.

(Here's a lesson - if you focus too sharply, and something goes wrong with your plan, what is your plan "B"?)

Anyway, his solution is to do a one year certification and get into science teaching at senior school level. There's big demand for science teachers right now and it's a very worthwhile career.

There are other career routes, too. You just have to have an open mind and be flexible about HOW you use your degree and your brain.