Are my presciption meds being watered down?

I had cancer surgery last year to remove stage III malignant melanoma and the 5 lymph nodes it had spread to. In the process many sensory nerves were severed and I was left with severe nerve damage causing me incredible pain. At 35 years old I didn't want to become opiate dependent (not to mention I would lose my job being on opiates) so after many trials & errors with different pain relievers, ultram did the best job. But in the past 2 weeks I have been dealing with flu-like symptoms, muscle & joint aches, fever like hot & cold spells, sleeplessness, ect.

I saw my doc today, he did bloodwork, and it came back normal. He asked if I'd stopped taking my ultram as these could be symptoms of withrawal & I said no. He said it might be a virus or possibly another autoimmune disorder (he believes melanoma is autoimmune as well) and referred me to see an immunologist for further testing.

I researched withdrawal symptoms for ultram & was astonished to learn I have nearly every symptom even though I take my generally low doses regularly. Then I came across an article of a pharmacist that had watered down chemo meds a few years back in my area. I'm not accusing the pharmacy, but what if the drug companies are doing this to stockpile or make $$? I know the FDA overlooks big pharma, but we all know how big govt works. Any thoughts?