Battery problems, not keeping it's charge, and sluggish performance

This happened yesterday, where my Surface started to become painfully slow all of a sudden after a restart. It also was not keeping it's charge; it was plugged in but sank from 50% to 20% overnight. I think this may be a battery issue, battery failure or a charger failure, or something else. I just want to have this confirmed so I know what is going on and can get it repaired quickly.

I have drained it to 5 percent, charged it to 50% and did it again, so it's kinda my fault