My pinky started feeling a bit "loose". it makes my performance/using and even grasping a mouse difficult. it feels like i have to multitask, and focus on it a bit to make it function. it can extend more than it should do, partly sideways?

I assume there has been no injury or finger pain. This may be some muscle fatigue in your 5th. finger from overuse at the computer. I don't think there's a serious enough issue with your finger to see a hand specialist at this time. Consult one if symptoms don't resolve.

This is quite odd in someone so young! Do you perform any repetitive motion with the pinky, such as in gaming or other repetitive hand motion? Any resting of the elbows for long periods of time? Any prior neck issues? In practice, I'd probably have you see an orthopedist or neurologist for a conduction study.