You're not going to get HepC from that activity. It's a blood to blood transmitted virus. If you had an open sore in your nasal passage, and shared a straw with an infected person who was bleeding, you could potentially become infected. But from a razor dividing up some coke lines? No way.
Also, you would not be having pain in your liver. Most HepC infected people are symptom free. It's not until the advanced stages of liver disease where you would possibly have some other manifestations.
Your mind is bending you over the proverbial barrel.
Well, from everything I have read, the danger of becoming infected with Hepatitis C while snorting cocaine has always referenced the sharing of the same straw. Cocaine (and whatever garbage has been added to it) is corrosive to human tissue, especially the nasal passages. If you snort enough, you can actually dissolve a hole in your septum. People who snort a lot of cocaine get frequent nosebleeds which sometimes results in blood getting on the end on the straw. Then the next person puts the same bloody end of the straw in their nose and if they have some damage to their nasal membranes (sometimes caused by pushing the straw into the soft tissue), there is a potential route for the virus to enter the bloodstream.
Congrats on being aware enough to use your own straw. The fact that you did that pretty much made this a non-risk event. I have never heard of anything to indicate that blood getting on the razor blade / credit card / etc. is a risk for infection. If you think about it, there is no reason to expect that there would be any blood on the razor blade. The blade is used to chop up the cocaine, push it into lines and then it is snorted up the tube and into the nose. It's not anything in the cocaine that is causing Hep C infection, its the blood on the top end of the straw that is the problem.
As for the pains you are feeling, it is too soon for the virus to start damaging your liver. Hep C is slow acting and can take decades to cause problems. What you are feeling physically is more likely to be caused by anxiety. If you were to show signs of an acute Hep C infection, they would take around two weeks to appear and would be general flu-like symptoms (fever, fatigue, general muscle soreness, and nausea). Most people do not feel any symptoms at all.
Here's a statistic that might ease your fears: In health care settings, doctors and nurses who accidentally stick themselves with a needle that has just been used on a patient that they know is Hepatitis C positive only are infected at a rate of 3% of the time - 97% of the time, nothing happens. What you did isn't even close to a bloody needlestick, so even if there were somehow Hepatitis C particles in the cocaine, your odds of becoming infected are approaching zero.
So, I really do not think you have anything to worry about as far as becoming infected with Hep C. Take this as a learning experience and don't do cocaine ever again. Cocaine can cause heart attacks and when it is "cut", you have no idea what chemicals have been added to it. I would be much more concerned about the effects of the cocaine rather than any risk of Hep C infection. And if drinking seems to lead you to reckless behavior, you might want to take a look at your drinking habits too.
Other than that, you are good to go.