Pet Scan Negative- Need Advice Desperately - 1242057

I am so LOST!
A little history.. In Feb 2011 I had elevated proteins and globulins on my lab test sent to a specialist who ran an SPEP and it was negative. In July I weighed 179 and today I weigh 138 with no appetite. I have had a small lipoma in my lower back for awhile now in October 2011 I started having very localized pain in my lower back while unconsciously rubbing the area I discovered the top f my hip bone has a solid mass on it; it has grown and is causing considerable pain. Repeat labs in December show an elevated creatinine and globulin elevation remains. Sent for CT scan to look at mass; it did not show up at all a small hematoma showed in the general area only. I have in the last wo months become very tired all the time, increasing lower back pelvic girdle pain (to the point of requiring narcotics to take the edge off and it's waking me up frequently through the night), occasional night sweats, a consistent low grade temperature 99.9 to 100.1. My dr finally decided to send me to a bone marrow specialist but did ask for a Pet scan first; the scan was negative. I feel like I am dying :-( I ad a hysterectomy in 2006 and am ony 32 years old. No pre-cursor injury either. No history of back pain or back injury. It's more pelvic girdle then back pain. I see te oncologist/bone marrow specialist on Tuesday.

Any ideas? Suggestions? Having had a negative pet scan means no chance this large mass (fist sized, solid, no movement, and visible as well as palpable) and pain s not cancer right?

Thank you.