Changed from Lexapro 20 mg to Zoloft 100 mg?

My husband has been on 20mg of Lexapro for 4 1/2 years. He recently became a police officer and due to the high stress level of the job has started having anxiety attacks on his way to work. His PCP changed his medication to 100 mg of Zoloft. So pretty much he stopped the Lexapro cold turkey and started taking the Zoloft. His anxiety is ALOT worse and within the week that he's been off of the Lexapro he's only been able to work 1 day. He is also having the attacks at home and not just on the way to work. I am worried he is going to get fired for missing so many days since he's only been working there a few weeks but I know he can't help having the anxiety attacks. I just wish the Zoloft would hurry up and kick in!