Ever go to the dentist and get numbed? You recieved a cocaine derivative. That is an amphetamine. Cocaine is widely employed in nerve blocks, and is still in limited use as a pain killer in certain conditions outside of nerve blocks. Amphetamines have the ability to potentiate opioid analgesics to provide superior pain relief. Very rarely they are given to combat the sedation common with opioid analgesics, and for certain chronic pain conditions which cause excessive fatigue. They are also sometimes employed in management of cancer pain. Though in many cases this use is considered "off-label", once a drug is approved - doctors may use it to treat any condition - even ones it wasn't approved for - that doesn't strain medical logic.
A wide variety of medications approved for other purposes are used "off label" in pain control, everything from antidepressants to anticonvulsants...
I have no idea what particular drug she is taking or the reason she is taking them (RSD perhaps? Cancer? Some type of vascular condition?), but if you could find out I would love to hear it. The "only 2 other people" thing smacks me a bit the wrong way unless it's some experimental compound, or a drug which was banned or more highly restricted for use in the US that they had to apply for an exception for - in which case it could be *anything*. Pretty much all of the amphetamines will show up on enzyme pannel style drug tests(the most common drug test), and that test does not make any distinction between them. I'm not sure what the MS/GC test results would be as that is outside of my knowledge. While the explanation sounds a little suspicious, it's not outside heard of medical practices... If it doubt, keep pressing.
Perhaps a quick look at some of the literature would help you:
Sasson S, Unterwald EM, Kornetsky C (1986) Potentiation of morphine analgesia by d-amphetamine. Psychopharmacology (Berl) 90(2):163-5
Shimm DS, Logue GL, Maltbie AA, Dugan S (1979) Medical management of chronic cancer pain. JAMA 241(22):2408-12
Kulkarni SD, Joglekar GV, Balwani JH (1967) Modification of aspirin analgesia by amphetamine. J Exp Med Sci 1967 Jun;11(1):14-7
Webb SS, Smith GM, Evans WO, Webb NC (1978) Toward the development of a potent, nonsedating, oral analgesic. Psychopharmacology (Berl) 60(1):25-8
Mancini I, Body JJ (1998) [Treatment of cancer pain: the role of co-analgesics].[Article in French] Rev Med Brux 19(4):A319-22
Dalal S, Melzack R (1998) Potentiation of opioid analgesia by psychostimulant drugs: a review. J Pain Symptom Manage 16(4):245-53
Reich MG, Razavi D (1996) [Role of amphetamines in cancerology : a review of the literature].[Article in French] Bull Cancer 1996 Nov;83(11):891-900
Ahmed SS, Joglekar GV, Balwani JH (1966) Potentiation of the analgesic effect of codeine in rats by d-amphetamine. Arch Int Pharmacodyn Ther 1966 Jan;159(1):185-8
Nott MW (1968) Eur J Pharmacol Potentiation of morphine analgesia by cocaine in mice.5(1):93-9
Connor J, Makonnen E, Rostom A (2000) Comparison of analgesic effects of khat (Catha edulis Forsk) extract, D-amphetamine and ibuprofen in mice.J Pharm Pharmacol 52(1):107-10
Piercey MF, Moon MW, Blinn JR, Dobry-Schreur PJ (1986) Analgesic activities of spinal cord substance P antagonists implicate substance P as a neurotransmitter of pain sensation. Brain Res 385(1):74-85
Are you numb yet? No. AARRGGGGGHH! I told you I wasn't numb! Sorry, I didn't believe you.