Help Battery charging issues

I couldn't find anything exactly like what I'm experiencing, so I'll lay it out. I was recently out of town using my stock phone charger in a hotel lamp outlet when this problem suddenly started. No idea if the outlet had anything to do with it, or if it's just a coincidence - just giving a background.

I use Battery Solo widget to monitor exact percentage of battery life, so I can see accurately what my phone is doing. It now charges to 80% and never goes past that point. I cannot through unplugging and replugging get it to go beyond there. Also, the battery seems to die about 2-3 times faster than it used to, and when it hits about 25%, it immediately starts with the blinking red icon, and shuts off within a few minutes. It's as if it's barely charging at all to begin with, and dying exceptionally quickly towards the end. I can't help but think I somehow fried my battery or charging port somehow, but that doesn't really make sense.

Anyone experience similar symptoms or issues and can offer any assistance?