Tina, I'm so sorry you're feeling so bad. I can relate. I have done this many times----and I always regret it.
My doctor once told me that to wean yourself off these type meds, you should reduce the dosage by 1/4 the first week, another 1/4 the second week, and so on until you are off of it. Anything quicker than that and you feel like you do---irritable, like you're going to crawl out of your skin, and 100 X worse than with any PMS!!!
Now that you've started it back, you should feel yourself again, but it will take several days. Usually, I'm myself again by 48-72 hours.
As for the doctor telling you the AD doesn't help for IBS, she obviously knows nothing about IBS. I hope you can find another doctor that can help you! Maybe if you explain how much it has helped you and how poorly you felt when you went off it it, you can get a new prescription.