Why did my iPhone shock me?

So I have an iPhone 7, and I've had it for about a year and 2 months. It has never given me any problems. The charger works and it runs fine when plugged into my wall, however, I just plugged it into my computer and noticed that when i picked it up, my right index finger started to hurt, so I put my phone down. It went away, then my finger got shocked when I put it on the finger scanner, so i put my phone down again. I noticed anywhere metal on my phone that wasn't covered by my case shocked me while it was plugged in. It wasn't static because it was sustained the entire time it was plugged into my HP Desktop. I unplugged it and plugged it back into the wall and it was fine, no more shocking. Any idea what's going on or if I should be worried?