Go back to Lamictal
if auras are better controlled
From the information provided by you, I learn that you are a patient of epilepsy
who underwent surgery for the same in Aug 2003. But I do not have the details as to what type of epilepsy you had, what was the seizure semiology(events chronology during the attack) and what surgery you underwent. The choice of antiepileptic drug depends on the type of epilepsy, apart from your other clinical profile. If your seizures/auras are better controlled with Lamictal than with Topamax, it is better to go back to it. And if it's still causing those hives there are other drugs which may be of help to you like carbamazepine
These medicines need to be monitored closely by a physician. It won't be an easy task for you to do that without your physician's help. So I recommend that you get back to the doctor whenever possible.
If you have any further queries please feel free to get back to me.