Been there, done that!
That's the bad thing about extremely low calorie dieting. Your body gets used to it, and anything more creates a gain. It thinks you were starving, so you need to convince it otherwise. I suggest you eat as healthy as you reasonably can and start upping your calories and normalizng your exercise routine to something that is more sustainable. You may very well gain some, but I guess that's the price you have to pay. I lost 20lbs in two weeks once by eating less than 400 calories a day and exercising 2 hours a day. But I gained it all back when I had a near collapse and had to resume normal eating. My body was STARVING and it held onto every bit I gave it. But it evened itself out over a short period of time, and I started losing again at a healthier pace.
Your body is recovering right now, and things are little off. You keep at what you're doing, and you'll see an improvement. A few days isn't enough to correct half a dozen binge/starve cycles. You're also probably gaining water back as well. Lack of BM's can be caused by dehydration and all the problems you're experiencing are probably from the dieters tea upsetting your systems normal balance. When I have a stomach bug, it takes me 3 whole months fully recover. Not all of us have systems are resilient to such immediate drastic changes!
I know how hard it is to have an eating disorder. I struggle with it everyday. But I think you're back on the right track and whatever weight you may gain, keep it in perspective that your body is reacting to what you did to it. It doesn't mean it's going to keep going like this, but you need time to recover. Stay off the scales a few weeks if you need to, if the numbers are going to trigger a binge. Also, if you're eating alot of carbs, that can make you overly hungry and make you want to binge. I understand being vegan, I tried it for a few months, but I'm sure you can find some recipes that aren't carb loaded. One thing I ate alot was a tofu scrambler. It makes it look like scrambled eggs, and the flavor is rich and spicy and all that tofu is filling. All I used was soft tofu mixed with some tumeric, garlic powder, onion powder, paprika, and crushed red pepper in a skillet and voila!