From what I've experienced and learned from others and in articles, it can really vary. Length of time on a medication, dose of a medication, individual reactions, and/or other factors play a part. Sometimes switching to similar medications immediately can help avoid withdrawals, but sometimes not at all. Please tell your your psychiatrist what you are experiencing. I hope they can help alleviate your discomfort and depression. Perhaps they should have more gradually made the switches? Or perhaps some of your discomfort is withdrawal, and some not withdrawal, but now being insufficiently medicated? This is just brainstorming. I'm not qualified to do so like your psychiatrist is.

I've had cases when a switch resulted in zero withdrawal. I've had some where my withdrawals were rough. In the latter cases, my psychiatrist weaned me off the medication(s) more gradually or made other medication adjustments that helped. Some of these weaning off periods, for me, have taken as long as months. If my psychiatrist didn't wean me off, but took me off cold turkey, either something really major happened, or if not, the withdrawals passed quickly. It sort of depends on the severity of the withdrawals sometimes, and if they can be alleviated with something simple.