Scared of brain tumor-sense being on antidepresants & quiting them- have had random muscle twitches & extreme fatigue-ct was clear- should i b worried?

Not sure why you got: a CT scan in the first place. The work up for random muscle twitching would include blood tests (thyroid, electrolytes) and possibly an EEG. If you have twitching of the tongue I would consider and EMG exam to exclude motor neuron disease. Both Pristiq (desvenlafaxine) and Welbutrin can cause muscle twitching as can excessive caffeine. Welbutrin can cause seizures.

SSRI Withdrawal: Some patients have severe withdrawal symptoms on stopping the newer antidepressants like SSRI's. If your medication was stopped all at once, instead of slowly tapered, this is more likely. The symptoms will stop as soon as you restart the antidepressant. Tapering the dose slowly is a bit less likely to cause withdrawal. If still having withdrawal symptoms ask your physician to switch to Prozac (fluoxetine)