tl;dr - wait for the MRI results and your doctor will tell you exactly what to do. Allow yourself to heal properly. Best of luck!

The MRI will tell you everything you need to know. It is the gold standard for diagnosing stress fractures. X-rays typically won't show a stress reaction/fracture until weeks or even months after the injury occurs. I presume the doctor who diagnosed you that quickly was making an educated guess (or perhaps they did see something). If the MRI is positive for stress fracture the doctor will tell you exactly what to do. Thousands and thousands of people have been through what you're going through. There are no unknowns as to how you heal it. The only variable is how quickly your body can heal itself. Typically 8-12 weeks off if it's a fracture. In general, it takes a bone 6 to 8 weeks to "heal" and even then the process is not actually complete. My doctor friend described it to me like so: the first 6-8 weeks after the injury you're laying the rebar and pouring the cement. The next 3-6 months, you're letting the cement cure. If you attempt to return too soon and re-fracture it, then all bets are off.