Injury before marathon

Just over two weeks ago, I experienced some pretty horrible calf pain on a five miles run. Went to doctor, sent to PT… Inflamed tibia… I was told not to run but am allowed to cross train with tons of strength, elliptical, and bike.

I just went to my second PT session and they still don’t want me to run. My race is October 15, and while my PT is hopeful that I’ll be able to do it, I’m so worried I’m losing fitness even though I’m cross training and won’t be ready. My PT reassured me I won’t lose fitness in such a short time, especially with x-training and because I’ve already hit my peak 20 mile run.

Any experience with this? How to cope? Especially with the nerves?