Hello. I'm 17 years old and i dont feel well.

for the past month ive had this headache. nonstop. and now i can hardley eat and when i do i cant keep my food down. I've been having these pains in the left side of my abdomin and sometimes around my abdomin and my back, on my left side, it feels hard and it hurts. its unconfortable to sit when its like that. I've had really bad salvation problems too. I have to swallow almost ever 5 seconds and it feels like im swallowing thick syrup. please help?