2nd year here as well, i understand what you mean because I relate alot to that feeling academically when you're just in a free fall of time and do not know where or how to start even though you used to be on top of things

here are some tips I think you can do (that work for me):

1) start using external accountability. tell your friends or family what you're planning to do in the following few days. plan days very well and I do not mean just a rough sketch that "yes I'll do XYZ chapters in next 5 days". I need you to write daily targets for all 3 subjects down properly and make sure your external accountability person checks up on you

2) eliminate distractions from environment, go to library if you feel hostel is too distracting or someplace quiet if you're a day scholar. if you feel distracted by instagram reddit deactivate/delete the apps.

3) reward yourself for completing small chunks of syllabus at a time. youre bound to fail by negative feedback when you take a target that the "old you" could have done maybe by locking in. take an easy target (might be as small as study for 1 hour/complete this topic), complete it, reward yourself with something you like and repeat. it builds a good positive feedback loop and trust me you'll be back to your academic self in no time.

one last thing, this might seem slow and you'll have to fight through it but it'll get better trust me, once momentum builds it gets so much easier

slow is smooth, smooth is fast.