First things first; see a sports physio, dont try to come back until your current injuries are mended fully. Minor injuries have a nasty way of becoming much worse injuries as the mechanics of your movement changes to compensate for injuries your carrying.
Secondly, (if your not already doing this) look at incorporating resistance training (body weight high intensity circuit exercises being ideal) as a means of building strength as well as cardio. I started working with a personal trainer, it's torture at times, but the best thing I ever did. Stronger and fitter than I have ever been at 40. The PT worked out my weaknesses within 20 minutes and puts me through routines every week which improve on them.