I Have Been Taking Lithosun 400 Mg Since 5 Years

i have been taking lithosun 400 mg since 5 years along with epilem 300mg but now i have been adviced to only continue with lithosun as epilem is effecting my liver and caused it to enlarge .
the problem i m facing now is at times my brain stop functioning effectively , i become too slow in getting things done . i am not able to communicate well with peoples and find it difficult to phrase a sentence and this goes on for approx 10 days .then after 10 days i feel to get along with people , i communicate well . confidence is back again .
please advice me on the problem i m facing