You need to see a well-qualified orthopedic or sports medicine Dr now. Does anyone that you know have a good Dr to recommend for a knee injury? When arranging to get an immediate appointment make it clear that you have swelling at more than one location, instability plus your other symptoms.
Don't do tests to see what makes it hurt.
(Is a torn ligament attachment to your bone what is causing the swelling, some other torn tissue?..........)