That's a long time I'm out of school.
The truth is you should read books about subjects you're interested in to solve a lack of understanding on one subject, and from there teach yourself anything you want, if you were in my situation.
What I did is taking the highest level course I could find on X subject, and trying to understand from other lower level sources the high level concepts I couldn't understand from intuition by the sole reading of the high level syllabus.
