These include muscle weakness, loss of bowel or bladder control, loss of sensation particularly in the pelvis,
and severe
and progressive
pain. The workup for this would include clinical examination, MRI, and EMG/NCS. Twitching can be from stress/caffeine, benign fasciculation syndrome, neuropathy, ALS (typically with other features), abnormal metabolic values (such as with calcium or thyroid), etc.
I would recommend that you be seen by your primary physician regarding these symtpoms.