Should I See My Doctor For This Skin Infection, Or Can I Let It Heal On It's Own?

I'm wearing a cast on my lower leg, and I noticed that there was an itchy lump on the inside of my shin, so I scratched it using a ruler (I know, stupid idea.) Now it's super itchy and it's a moist area that's been scratched raw and when I smell the inside of my cast there's a strong odor... I'm not sure how to describe it, but it just smells bad. And sometimes when I stick something into my cast to check on it, I get this smelly reddish-brown discharge. I'm pretty sure it's infected.
Still, I get my cast off in two weeks or so... can I just wait it out? Maybe it will heal on it's own if I leave it alone (which is easier said than done--it gets so itchy sometimes!) I just don't want to come complaining to the hospital again... I already made them readjust it a week ago! Plus they'd be annoyed that I'm sticking rulers into my cast!