Yes. It's normal to feel an upset stomach, get stomach cramps, or even feel like vomiting after Magic Truffles have consumed. Furthermore, when the first effects begin to appear, it is normal to feel intoxicated or like you are taking something bad, or similar discomforts.
When you vomit, in most cases you still had food in your stomach or you have a very sensitive stomach (in general or only for Magic Truffles). That is why fasting before every trip is recommended. This helps to prevent or reduce such complaints.
See also: Preparing for a Magic Truffle Trip
What to do during a bad trip?
If a friend is having a bad trip, try to comfort them and help them realize that they have taken psychedelic drugs. It's normal for your friend to feel this way. Try to be as gentle as possible, but also give the person enough space.
Most bad trips end with a real circular thought that just goes round and round in your head until it becomes inevitable. This realization just buzzes in your head and will continue to do so until you accept it. After you accept that thought and “let it go,” it's like a super-fast ray of light that goes through you. Everything becomes okay in a fraction of a second. You go from the worst-feeling person to the best-feeling person. in no time.
You might make drastic choices in your life after a bad trip. You break up, move to another city, quit your job, start exercising, begin eating healthy, spend more time with your family, or drop out of school. Because a bad trip is simply your subconscious telling you that you're doing something really wrong.
When someone around you is having a bad trip try to support to comfort them, but realize that the answer lies within themselves. They need to let go. They need to realize something about themselves. It's personal. In addition, you can help them by; giving them something to eat, comforting them, and calming them down. Also talk to them, let them talk, and remind them that this is only temporary. Most importantly, if they try to tell you something, you need to listen carefully and try to help them in their search.
Always handy during a bad trip: The trip stopper