Depending on how long you were on Lamictal and then stopped it could explain the rage.... Did you get checked out by a Doctor when you broke out in Hives? It might not have had anything to do with Lamical.. Only a doctor can tell the difference.

Rage-y feelings are a part of Bipolar and even on a great combo of meds Bipolar can and will pop out and slap you very hard.. It's sneaky like that.

What coping skills are you using to help ease the rage?

Exercise is great , helps burn off some anger in most people.
Meditation
Mindfulness
any kind of soothing activites , I love reading and often can get lost in a book and get a break from being so angry.

Maybe a call to your Pdoc would be helpful? but regardless of a med or not , you can never have enough coping skills and when needed keep flinging coping skills at it until something sticks.

Hope your feeling better soon