I did, however i was also placed on seroquil, and some other meds at the same time, so i don't know which ones were doing what. But, now i'm just back to my old clumsy self, and not a stumbling, unsteady self. lol...
The biggest thing with any dose changes with Lamictal is to watch for any type of rashes that may develope. Those can be serious if caused by the med.
If you continue having troubles tho, I would call your pdoc and ask him/her if it's something you should be worried about, or if it will pass soon.. He/she might be able to lower it, and do a slower tapering upwards. 100 to 400 is quite a jump (i think), cause i was on 25, then 50, then 100, now 150.