I understand that you just had a MRI and earlier you have had fluid drainage
with cortisone injection
Coming to your MRI findings, horizontal tear body and posterior horn of medial meniscus
and subchondral cyst
formation, there is a need to see an orthopedic surgeon.
The situation is not serious but there is always a discomfort associated with meniscal tears.
If your doctor suggests, please go in for a curative surgery. This will improve your quality of life to a great extent.
Hope this helps.