Another running injury. Can I cross train?

So After pulling my adductor about 8 weeks ago and recovering I have got another injury.

I now have a muscle strain in my back, just below my shoulder blades. What is it with running that I keep getting these type of injuries????? I guess it's because I am increasing my speed and moving my arms more. Could my HRM strap be causing this? It's kind of level with where it hurts.

Anyway, I guess I can go on the excersise bike for the next week. I tried 15 mins yesterday to see how it went and I am OK but a bit sorer than yesterday. Today is supposed to be my long run day. Should I just rest up a week or hammer in a long bike ride?:ohwell: