I'm sure I've brought this up before but it is worth repeating: no one goes to their doctor and says, "You know, I think my cancer is hurting!" And in my case, that was true as well. It was persistent lower back pain that began my circuitous route to diagnosis - when I just couldn't shake a nagging backache and began taking the time to figure out what the origin of the annoyance could be (we're all always too busy to schedule the time to see a doctor).
Though I caution against relying on sites like WebMD as a diagnostic tool for any disease, it can be a beginning point for further exploratory or motivation for professional intervention/examination. In no particular order of importance or probability, here's a list of a few of the many varied symptoms of Multiple Myeloma (MM): Bone pain, Posture changes and loss of Mobility, Kidney damage, Frequent infections, Blood clots and Abnormal bleeding, Fatigue and Weakness, Neurological problems, Neuropathy, Gastrointestinal issues, Skin problems, Swelling of the extremities, and even Depression.
In much the same way that each cancer patient's disease is different, so too, their symptoms can vary dramatically. No one individual would have all of the above, and as you can see from the many variations listed, it could be difficult to isolate having MM from any one or combination of the aforementioned. In my case, during the months prior to my eventual diagnosis, there were a number of things going on with me (and within me) - none of which screamed MM, especially to the unsuspecting or uninitiated. Of course, in retrospect they all take on a different significance. I was a little tired, I had lost some weight, my skin wasn't as "pink" as usual, I would get hoarse or out of breath when talking, I would get dizzy when laying flat, and paramount among them all - the ongoing lower back pain that I mentioned before (that turned out to be the early stages of renal failure; which my Onc team was able to arrest and reverse).
I want to repeat and re-emphasize my warning about jumping to any medical conclusions on your own after a visit to a health website such as WebMD, etc (this is by no means a condemnation of WebMD). But if something feels wrong or off for an extended period of time (consistently awry for more than a month), it is well worth getting checked out. The best that can happen is that you will be reassured that nothing is wrong. And the second best thing that could happen, is that if it is cancer or something similarly problematic, you will have potentially caught it early - which is always the optimal way to confront and remedy a serious medical issue. If you have any doubts, don't ask your relatives, your friends or your neighbors: go see a GP, get a blood test or two, and tell your doctor where it hurts.
