Q:

Is camera damage causing these severe diagonal lines from concentrated light sources?

Since a week or so, I have severe diagonal stripes around light-sources in my night-time photographs on my Canon Powershot A650.  In the past, I had some (I guess due to Fraunhofer diffraction, see below), but not nearly as severe as now. It started when I tried to clean my lens, because there was some droplet on it. Did I irrevocably damage it?

(The green stuff is Aurora Borealis, photograph taken from my bedroom window)
Related questions, but I think it's still different:

Why do light sources appear as stars sometimes?

A:

Looks like flare caused by some kind of oily residue on the lens. I wouldn't say you have permanently damaged it, although that may be a remote possibility if you scratched it or maybe etched away any of the multicoating. 
I would find some photographic lens cleaning solution and a nice microfiber cloth, a soft camel hair brush or a LensPen, and try to clean it better. Use the brush to dust off any particulate first. You don't want any particulate of any kind on the lens before cleaning it, just in case any of it is harder than the lens and capable of scratching it. Use the microfiber cloth and cleaning solution to clean the lens and hopefully get rid of any residue that may be on it. 
On photographic lenses, you might be amazed at how even the oil from a fingerprint can affect flare, and how well that same finger oil will stick to the lens like glue. You can only really get rid of it with at the very least a microfiber cloth or tissue...and when that doesn't work, an appropriate solvent that won't damage the lens.

