I get chills alot. When I started taking my temps when I felt a chill coming on, I usually had (have) a fever. It may be low-grade (between 100 and 101), but it counts as a fever nonetheless. Mtx can lower your resistance to all kinds of little viruses; perhaps you've picked up a bug somewhere? If the chills don't go away, I would let your doctor know about it. I don't think mtx causes the chills, but you can catch all kinds of things on it, as it is an immunosuppressant drug.
Current dx: Rheumatoid Arthritis
Suspected dx: UCTD/Early Lupus
Current Meds: Enbrel, Plaquenil, Aciphex, Ultracet, Zyrtec, Allavert-D, Zantac, Tylenol PM
Past Meds: Relafen, Vioxx, Mobic, Voltaren, Sulfasalazine, Entocort, Prednisone, Humira, Reglan