antidepressenannt advice

my neurologist says I  have symptoms of fybromyalgia and may have possible mild ms. he has me  on 100 mg of zoloft.    I  recently visited my regular doctor and  mentioned I was having a lot of wide spread numbness that comes with movement, the faster i try to work on production the worst it gets. It causes me to get dizzy and have other symptoms to. he put me on elavil 25mg. my qeustion is is it safe to be own two different antideppressants at the same time.
Do you think the fybromyalgia is causing my numbness problems.

                                                                                                        thanks roaseanna