In 28 years living in Germany, I've never encountered that word.
Also, quick online search only lists English sources.
If it was a German word, it would mean "the pain of being happy/lucky" (Glücksschmerz) or "the pain of clucking like a chicken" (Gluckschmerz)
Also, before you get too jealous of the German language, here's two words we don't have
Awkward and anxiety
It's so awkward you can't even say how awkward it is, and according to my dictionary social anxiety is the same as social phobia
Trying to explain to my psychiatrist that I had a minor anxiety attack for no reason is gonna be awkward to do when it's translated to "fear"