I have a similar problem with a rib. I cannot work the guard or have any weight on top of my chest. Because of this I have been doing tons of rep work. I have also done some light live drilling trying to pass the guard of my training partners. If I get swept, my partner knows not to mount or assume side control.
I am getting better at passing the guard. My training partners are great and generous with their time in drilling with me.
With that said, injuries suck.