Possible MCL Grade 3 tear immobilization and treatment, recommendations?

[crouton]

In the beginning of august I had a bad fall. I was put in a knee splint. After an MRI it looks like I have a grade 3 MCL tear. Prior to that, I've had habitual dislocation of the patella. Today, the doctor said I might have never had a connected MCL since my knee would "travel" with every step (and I could walk and function completely normally, before the injury). The doctor said that I should be in a splint for another 2 weeks (total of a month), the reason being - I have about 20-50mL of liquid still in my knee joint (I've already had an aspiration). Is that something normal? I'm afraid that my muscles will atrophy in my knee and I won't be able to walk after such long immobilization. I'm on crutches, although if I limp without crutches - there's no pain. He told me NOT to do any exercises and not to take off the splint - only to shower. The doctor also said that doing surgery to bring together the MCL isn't worth it because then my knee will stay in place and I might not be able to walk (like I said, normally my knee "travels" to outside of the knee. Ex. right knee - patella goes to the right when bent. Vice versa on left). He never did a valgus stress test...

Is the doctor recommending the correct treatment plan? Should I really not exercise, even just a little? Is there anything you can recommend? Like I said, there's no pain when I walk, but he still says to use crutches...

Thank you!