I think you should have a long sit down with the school psychologist.
NOT the school counselor, they usually have no official education pertaining to psychology, they often have been teachers that want to help more, in the sense of helping kids work through short term issues that should be resolved 100% at school. Such as conflicts with friends, teacher/student issues, bullying, making their class schedule. They serve a great purpose but they are NOT a mental health professional.
This school psychologist will have a Ph.D after their name on their letterhead or LPC, perhaps an MSW instead. Those are the people that are professional mental health people.
Again, not saying anything against school counselors, this is an obvious long term mental health issue.
They need to advise you about the school issue. My first thought is to take her out of a ghost infested place so she won't be so scared. BUT it's nearly the end of the year, if she has friends that really care she needs them for peer support, she may benefit from being around her ghost friends too. Do they talk to her? Help her in her school work? Tell her the answers on tests? Not joking, they may just be her subconscious mind filtering the information she has learned and getting it back out in a unique way.
A lady I knew had Schizophrenic. She had some money issues and couldn't fill her prescriptions so she ended up in the hospital mental health ward for a few weeks. One of the things she told me was that when she didn't take her meds and was able to hear the voices it was like running in to long lost friends. Inside she was so happy to find them. They also gave her advice about foods, exercise, etc...so she ate healthier during that time. Now that doesn't mean really healthy, it was a hallucination after all. She was a fully functioning person that held down a stressful job. She was the office manager for a construction company and she did an excellent job. They were really upset with her for not letting them know she needed money for medicine. They told her if she ever needed medicine again and didn't have the money she was to come to them. They really cared about her.
Back to your daughter. She's really young for a psychotic mental health issue. My heart breaks for her. Meds will make her life more livable but she has to stay on them and take them regularly.
She may be seeing ghosts, I don't doubt there are some there. One of my college professors in Sociology did his thesis on Rose Colored Glasses. The idea was WHO sees the real world? The mentally ill who see things we don't see? Or us, who don't see what's around us, we may even feel their presence but we don't look because we don't want to know.
I think her brain is having a delusion though. She needs to go back in the hospital and have a complete work up if they didn't do one for her there. I mean the whole shebang, PET scans, MRI, blood work, X-rays, MMPI, a sleep study to make sure she's not sleep deprived, full exam by a neurologist, and more.
She needs to be tested for so many things. I hope you have this resource and they find something tangible where psychosis isn't the cause but the result of something that can be fixed quickly. If they did that already and you are satisfied with their findings then that is a good step. She is going to need you full time. The summer is coming up and you'll have her full time. You will be able to pick up on med issues, if they're working or not, to see her grow or decline, and you need support to.
Please find a mental health support group. They don't sit around talking about their mentally ill family member, they sit around and share how stressed out they have been, how to take time and have a date with hubby, what new resources are in town, who's a good doc and who's a quack, and simply hearing how others are coping with the stress, the hopelessness that they often feel, what to do when someone is having a bad reaction to a med, and more. You should come away from these meetings feeling hopeful, resigned and focused on a new goal, and overall in a better frame of mind.
So, to sum it up. If she hasn't had a lot of testing done try to get more done just to cover all the bases.
Make an appointment with the school psychologist so you can get out of the hot seat and get them on your side to make the absences go away and have options for her education the rest of the school year.
Then find a support for yourself, so you can feel happier and calmer and get some of the stress off your shoulders.
I pray for your family. This is a highly stressful time and I want you to know there are millions of people with mental illness right now who are working and supporting their families, they have lives, they are successful, and she can be too. With the right med combinations and counseling and support she will do well.