ACL tear or just a bad sprain?

I was recovering from ACL surgery until I played b-ball and my knee gave out when someone much bigger than I ran me over. I felt/heard a pop and was in pain. That was about 30 days ago. Saw my dr last friday, he checked my knee (no MRI) and said he felt two end points, he doesnt think the acl is torn and he thinks it's just a bad sprain and I should be good in about a month. Is it possible the pop I heard could be another ligament damaged? Anyone think I should request an MRI in a month or just go with the Dr's word?