Flunil 40

What is serotonin it make my life hell I am taking flunil 40 mg earlier 20 mg. I had taken many medicine since last 5 yrs like van tab new man od since last 2 months taking fludac / flunil and for the first time I am seeing bit difference .but with the worries of side effect

I want to know whether flunil 40 is safe during breastfeeding

I have been taing flunil 40 since last year.... But now it is not available at my nearby shop. So can I use fludac in its place as both have the same composition?