You need to go to the ER. If your mom won't take you, call 911 and go by ambulance. You can deal with the money issues later.

Persistent hallucinations need emergency medical care, if you can't get in touch with your psychiatrist. My guess is if you're not a danger to yourself or others, and you tell them you need Seroquel, they'll give you a script to last until your psychiatrist appointment and send you home. When the hospital wants payment, it can be dealt with. They often have ways to do payment plans, or in the case where you really can't pay they may write it off and not force you to pay.

Go to the hospital. You need it, regardless what your parents may say. You're old enough to make this decision. It's your responsibility.