Need Advice - Ortho doesn't want to give MRI

Hi everyone - i need some advice on if you think I should get a second opinion. About three weeks ago I *think* I pulled a muscle on my Peloton (this was not an injury where I felt the moment it happened no popping no immense pain during exercise) in what i thought was the bottom of my hamstring but after about one day I was having pain in the back of my knee when I put weight on it. Since then I stayed off of it for a week and got better but now ever since then my knee feels odd (like its floating lol) and I feel like I can't fully extend my leg. I'm having light pain in the left back side of that knee as well probably a 2/10

I finally went to the ortho yesterday and he took xrays and he said everything looked fine. I asked about an MRI and he says he doesn't think it's necessary and to just ice and rest my knee since there was no swelling or immense pain.

Should I get a second opinion? I've never had a knee injury before and I would hate to continue just doing RICE if something more serious is happening. I'm going crazy not being able to work out and or even really do stuff around the house.