Hi,this may be due to un-natural occlusal forces on the crown, this could be due to habit of bruxism,smoking, uncontrolled
sugar level. Already infected implant i.e. peri-implantiis or ill fitting crown may be a reason. Putting graft and waiting for 4-6 months and then get it done again seems to be the only choice now.
Next Steps
Better to to look into the causative factor and try to upgrade your implant and crown quality as well.
Health Tips
Get a temporary crown for this waiting period.