This could be a mild ligament injury
which may be causing this feeling of instability. I recommend you let an Orthopedician have a look at your MRI
as trivial ligament injuries like ACL tear may be missed easli by Doctors in a busy Emergency Room.
You can apply a knee brace
for now. Avoid playing for a while. Get your Orthopedic consult as soon as possible.
Wishing speedy recovery.