... in both arms at injection site and hardness of muscles. how did this happen. she also takes geodon tablet and cogentin tablet. she gets the perihalodol 100mgs by injection once a month. this is a new doctor for her.. the nurse gave her the injection in both arms and now they are infected and there is hardness of muscle, has anyone else experienced this:? as her caregiver is there something more i need to know, need to do. i don't have a lot of support as her caregiver. i'm trying to educate myself as much as i can, so i can continue to help her. she is currently living with me.