You can have your doctor contact the drug manufacturer's or you can go there yourself and either call the companies that manufacture your meds and find out what you need to qualify for your meds for free or at a huge discount. There is a thread on this forum some time ago regarding resources for patients in need that lists some of the websites and their contact information. You can search for it....
The good news is that you have made it thus far without the meds, and while I understand that withdrawal is uncomfortable, 5 days into it, you are or will be through the worst of it now....and you should physically start feeling better. I know that doesn't help with the pain levels, but it will help with the added symptoms of withdrawal and that in turn may help your body to ease some of the increase in pain, while your body begins to remanufacture your own endorphins to help deal with the pain.
Have you discussed with your doctor and pharmacist your problems with the cost of medications? They can offer generics for most medications and it may be possible for your PM doctor to change you over to another medication like methadone that is ridiculously cheap but works well for both mechanical and neuropathic pain.
As far as the seizure meds go, the drug manufacturer's have arrangements with doctors offices where they can send your meds to the doctor's office and you just pick them up there on the dates you need them. The doctor fills out what meds you need, and what amounts and the companies send them to the office.
Check those with your doctors and hopefully you will be able to find some of the resources or one of the mods can direct you to the thread that I was referring to....