I was improvising the other day in D# minor and my finger slipped and hit an A and it actually sounded GREAT! I loved it, so I went into dangerous territory and hit a D and that was also nice. It didn't go well with the times after it but you get the point. I now use this a lot when I compose. What is it? Does it have a name? Are my ears just trolling me? Please tell me, I'd love to look into this more.
Adding to ttw's answer, Victor Wooten did a great demonstration showing how to practice with chromatic scale. The goal is to learn how to make music with even the "wrong notes" and get them to sound right instead of just sticking to a particular key or scale. At one point he solos using only the "wrong notes". It's one thing to read about this in text form but it's another thing to hear it in action, and Victor is one of the best.
Classically speaking, there are no restrictions on which notes (out of the chromatic scale) that can be used in any key. Notes may have different musical meaning. A simple example is using passing tones between two notes (for example, if a tune has the notes G A in, one could insert G# going upward or Ab going downward between the two scale notes; this would not change the harmony.) Likewise there are neighbor tones which may be chromatic (a lower neighbor is usually a half step away so it may be sharpened.) Any of these notes may be on an unaccented beat (common, has little effect) or accented (less common though not rare, this has a big effect on the sound.)
Guitarist, right? You've learned a system based on 'what scale fits what chord' but you haven't spent much time playing the repertoire, past and present, from notation? You'd have found lots of this sort of thing.
As @Tim says, you've hit on two of the most commonly used chromatic notes, particularly in blues-influenced music (though the Cx hardly counts as chromatic). But all the other ones (not to mention non-diatonic chords) are up for grabs too. So much to discover!
It's more usual to spell this key as E♭ minor rather than D♯ minor. Not the least so that we can call the leading note D♮ rather than Cx.