25mg is a tiny dose. I don't think 25mg cause all your side effects, with possible exception of fogged mind, but everyone is different. Are you taking anything else?

Normal therapeutical dose of Lamictal is 200mg or more. But you have to go up in tiny steps. Increasing the dose by 50MG every 2-3 weeks. 25mg probably even better. Otherwise you'd risk some really serious side effects. I'm on 250mg and still feel awful.

Cheers