The instructions from the physio sound a-okay to me - I just got through a round of physio for a hip injury and actually, running mymics a hopping movement that they want you to do or something. I might be slightly off in the wording but it's not about the foot strike. Don't ever let a coach guilt you. As long as you've got a good physio that deals with athletes, they know what they're talking about.
Also, I don't know where the OP is, but I was thinking it might be Canada for some reason? Please correct me if I'm wrong. If so, it's not so easy to just 'go get an MRI'. But as I said, please correct me if I'm wrong on the location of the OP. This is one thing I'm slightly jealous of the Americans on in terms of health care. Other than wait lists, I'll take my free heath care any day!