I Am Having Severe Pain In My Knee Around The

I am having severe pain in my knee around the kneecap. I had a Mri and they didn't take the picture that was where the pain was. The Dr said, That ok we got what we needed. And wanted me to come for knee injections prp. That this was arthritis. I feel like I have a injury:( I was looking for answers online. There is no way that out of the blue that arthritis just kicked in at full force.