GO back to your GP and tell him you fear you might experience side effects.
The GP will either tell you you shall indeed have side effects, or shall tell you you won't.
If it's the first you can ask to slow down instead of a sudden stop, but the GP will most likely tell you it won't have side effects.
Either way you have no choice but to cope with however the situation turns out, you'll feel better after having spoken to your psychiatrist.