Appointment Monday

Got an appointment with the doctor next Monday about my knee. I called for a referal to a knee specialist, but they wanted me to come in to get checked out before I got a referral. Hopefully someone will be able to shed some light on what is going on. I fear that this my derail me from my marathon goal this year........well, there are other races this year I can still get ready for, half-marathons..............we will see.