Are My Period Pains Anything Serious? Every Month My Pains

Are my period pains anything serious? Every month my pains get worse, it's now at the point where if I didn't take painkillers I wouldn't be able to move. The pains started to get bad at the age of about 14, I'm 17 next month and I've never experienced pain like it. It tends to be mostly on the left hand side, but it often spreads into the bottom of my back and, occasionally, into my chest. I'm worried in case I have something seriously wrong. I've tried every single painkiller you can get over the counter (paracetamol, ibuprofen, neurofen, feminax, anadin, cocodamol, at 16-nearly 17- I shouldn't have gone through that many different types of painkillers to find that nothing is working).The last two periods I have had, have caused me to be sick. I Haven't been sick previously for about 8 years so it came as a shock to me. I don't know what else to do and I'm worried that if I go to the doctors, he'll tell me I've got cancer or something even worse. its worrying me a lot, especially now since I'm starting 6th form and working, so I can't risk any time taken off for the pain. I hope you can provide me with an answer,
Yours sincerely
Danielle