Hi Jennifer,
Sorry about losing you like that. I'll try again and I don't have the boss looking over my shoulder so maybe it'll make a bit more sense.
Unlike adults who can maintain a pretty constant body weight over years, children are for the most part on a very slow but stead increase until they reach adulthood. From birth until around 18 months parents often notice very rapid increases. Then the child seems to level out and grow slow - but often the child will experiance short but quick increases in both height and weight.
Jake's Trileptol is figured at 2 milagrams per kelo (sp). So his dosage could be as high as 15 milagrams per day while he weighed 30 pounds.

Jennifer, there is a formula that the Dr uses and I can't find where I've written it down SO please don't quote me on the that! But I think you get the idea!
Currently, he is only taking 12 mlgs per day. The Dr is letting him "grow" through the formula. Meaning that we could increase the dosage another 3 mlg per day if he starts to seize again.
The first several months he was seizing was like trying to hit a moving target. The Dr would increase the meds and he would go for days and sometimes weeks with out seizing - then bam! Here they were again... often this would center around gains of weight. Not so much now that he's leveled off.
So, if the Neuro is figuring Gage's meds based on a weight formula that could be what you are seeing. He has simply grown through the formula that was working for him. If you were able to get control at a lower dosage then you simply increase the med. But, after a while you could reach the maximam dosage recommended for that med.
As far as Dilantin... There are several people on the board who have had great luck with it and were able to gain control. For Jake the levels that were needed to gain the control were to high for his body to tolerate. There can be some pretty scary side effect to this drug. For a person who can speak for themselves fine and dandy... but for a child who can't talk and tell you what they are feeling - I would not encourage any parent to place small kids on it!
Hope that helps!
Love and light
Lisa and kids