hi sorry you are going thru this. 
Im sure if you asked them the dr will give you something to help you be a bit more calm and get some sleep. 
In the meantime try and take you mind off what you dont know yet. Your diagnosis is obviously very new and a huge shock to deal with. Write a list of your worries to take with you when you go for your next appointment. Try and turn the worry into being pro active about facing your diagnosis and what you can do about it and the choices you have. If you feel less not in control you will worry less because everything is understood and have taken charge of whats going to happen. 

its very understandable to be panicking and scared about it, the big C word is not the death sentence it once was and the treatments now are curing and keeping people alive for years. 
If you are worried about money jobs or treatment the mac millan nurses can help you with all those questions. 
if you have family and friends talk about your worries and fears about treatment with them and make sure they come with you to any appointments so they can support you if you feel over whelmed or bullied into having something you dont understand or are worried about. 
you will get through this,