After being on 50 mg of co-sertraline for a year and a bit should i be having withdrawal like dizzy spells migraines diarrhea and personality changes?

Discontinuation : I would expect you to have the discontinuation symptoms associated with sertraline if you've been on it for a year. These usually include irritability, lightheadedness, gastrointestinal effects, malaise, and even lhermitte's sign (electric shock sensations down the back, arms or legs when turning one's head). They'll go away after a few weeks. If unbearable, take an occasional 1/2 pill.

Suddenly stopped yes: If you suddenly stopped taking your sertraline without being gradually tapered off of the medication, you could have withdrawal symptoms some of which you've mentioned. Talk to your prescribing doctor to see if you should get off the medication and how.