I need help

Hi, I need help. I'm a teenage girl and I don't know what to do. I've been extremely sick since October. The doctors said they ran every test out there. I've had scans done. Nothing. Now they won't believe me. I went to the doctor because every time I attempted to drink water I would throw up, gag, my throat would close. They didn't even look at me, just told me I'm okay. I'm in complete agony every day with constant headaches and body pain. I'm on medication for them but they aren't doing anything anymore. The headaches hit at random times, severe enough I can't see, I can't speak, it will get worse and worse and then feel like my nose is bleeding but it's never blood. It doesn't feel like a regular runny nose. They said they arent migranes but all I can do is scream and cry (I know it makes it worse but I cant help it). I recently started having seizures again after being seizures free for over a year (non epileptic). It hurts so bad all the time. No matter what I take it doesn't touch it. I need help, no one believes me anymore. Please, I can't live like this. What do I do?