Knee Problems-Continued?

so i went to the orthopedic doctor today and he told me that he thinks i irritated my kneecap and it'll just go away after a while. i personally think i might have torn my acl. I know that "doctor knows best" but he took an x-ray and not an mri. he wanted to look at my knee joint but that's not my problem. my knee hurts all over the front, all over in the back only when i'm standing up though, and after this seven months it makes my quads and calf's twitch and kind of hurt. if you think those are symptoms of anything torn and i should get an mri please tell me so. Thank you in advance :)