I spilled black coffee and my macbook still works

Hi, my friend next to me spilled black coffee on my macbook almost 8 days ago. He spilled it on desk, it was a lot of coffee, but it was just power charging part, usb ports and plug in parts ( quite a bit on keyboard but didn't sink in) It didn't have any noticeable problem, so I just wiped it out and been using it till now. I was too stupid to look up how to dry out or whatever. After that weird things often happened but not always like this. When I put earphones in, the volume suddenly goes down and comes back up by itself, and when I type, the output got much slower than it used to be. I first thought it's just my macbook getting slower by time but this just never happened before. Thus, I wonder if there is a actual status check that what is wrong with my macbook. Can I just go to apple store? can they just figure out that it happened because of coffee or just from other things?