Eye contact

Life events have happened and I am now living back home with my parents. I’m a single mom with two kids. I’ve been back home for 8 months now and just recently my 18 year old sister has been acting weird. She absolutely goes off her rocker if I even so much as look at her. She can’t have a normal conversation with me that involves eye contact. I’m at an absolute loss because I can’t figure out what I did to her. I have asked her and she tells me I haven’t done anything she just hates eye contact. I don’t understand because she has made eye contact with me before just fine but the past week I’m not allowed to look at her?? I can’t even glance in her direction without her screaming at me not to stare at her. I need advice on how to go about this? I feel like I’m walking on eggshells around her and I’m afraid to even look in her direction because of how she reacts. I really just don’t understand.