Wow, nobody touched this question and I sort of understand why. It's a hard thing to discuss because it involves such subjective experiences.
I have trained as a Reiki Master however I only use it with the animals I meet and do not enjoy working with people on this level at all.
Your dreams do not surprise me. When a person involves themselves with a group of people at these levels of consciousness exploration, there are communications going on between you that no one in the group is aware of at the time. Dreams and physical sensations will be the avenue these sub conscious connections take to get to your awareness.
I think there are a combination of things going on here as your own energy is being re routed to accomadate the new point of view that you are growing into now. Reiki has entered your field of knowledge and you are seeking to flow with a better lifestyle. There are blockages that will become obvious as your energies shift and change and this requires you to be gentle but firm as you wear away the barriers. Obviously, you are capable of 'listening to your body' and you understand that something like constipation can be energy and stress related.
The other issue is that the people of your group are projecting their own fears and blockages onto the group consciousness and you are picking them up. Many Reiki groups and teachers talk about opening chakras, being open to messages and increasing intuition and such. This is good practice but too many of them don't talk about closing your chakras and protecting your inner world from too much outside information. It is very important to learn how to close yourself just as much as is is to learn to be open. Don't leave your chakras open or you will get more than you can handle.
Reiki healing in general is quite controversial and there are many differing opinions on it's efficacy. Embarking on knowledge of Reiki is not all angels, flowers and rainbows.
I am curious as to how you are doing now since this question was posted seven months ago.