If it was me I'd probably start by going back to whomever is prescribing the 20mg Fluoxetine (Prozac). They must have diagnosed you with something to prescribe it although they've maybe not talked with you about their reasons. Not sure how long you've been on that dose. It may not suit you although it is a fairly low dose.

http://www.drugs.com/dosage/fluoxeti...for_Depression

http://www.drugs.com/dosage/fluoxeti...lsive_Disorder

http://www.drugs.com/dosage/fluoxeti...Panic_Disorder