I'm worried about my little sister

> A few nights ago me and my girlfriend were watching a movie. It was late, about 3 AM. My sister is sleeping in bed in the room next to us.

> I hear a noise coming from her room, its very faint, I think she may be talking on her phone.

> I am unsure the amount of time I waited (it could be longer than 5 minutes) but i could hear the noises again.

> I start to worry because its abnormal. I knock on her door and ask her if she is okay... no response. I open her door and turn on her light...my heart drops.... I see her eyes wide open having a seizure laying on her back :(

> I put her on her side but she is still moving. She stops moving completely. Completely still. I am unsure if she is alive for 30 seconds. I try to reassure her that everything is alright despite mentally panicking. 

> I start to cry because I love her so much and I am unsure if she is alive.

> She regains consciousness and sits up and sees me looking at her. My arms are on her arms and I say "everything is alright you just had a seizure"  

> *I enter real life horror movie* 

> She looks horrified like she doesn't know who I am. Like I broke into the house and I was about to kill her. Her eyes are wide open and she is so scared of me, so afraid of me, she immediately starts to try get away from me like her life depended on it.

> I recognize I could look scary so I stop her from looking at me and put my girlfriend (who she had only met 1 time) in front of her (my girlfriend looks loving and caring). I tell my gf to smile. 

> My sister calms down and goes under her covers embarrassed.  

> I get my parents to handle the situation and leave.

I am unsure about my sisters condition. She is 20 and I know she has had around 30 or more seizures in the past few years. She almost always has them at night while sleeping. I am so scared for her. I am so worried for her. I listen out for her at night afraid. I feel scared for the next time I hear noises coming from her room. I feel scared for the next time I walk through her door at night :( 

Mentally I am in a dark place.

Is it normal for me to be extremely concerned? Is there anything I can do? Should I buy her a sensor to put on her bed? Will she be okay? What can I do differently next time? 

- Kind regards,

Josh