Strong Feeling in my body

Today I participated in a workshop of a counseling certification I’m doing. We had to do an exercise where we had to think about how we see ourselves in the context of the group and our relation to the group. Then we should find a body pose/position with gestures that reflects that relation and take a picture of it. Then we were in smaller groups and had to present our pictures and the others in the group reflected on the picture and how they see us in the group. As soon as I heard the description of the exercise I felt really stressed and tense in my body. I felt like the others would be judging me and that I couldn’t control how much I tell them about me. My neck and shoulders started to hurt because I was so tense. But I struggle to identify the thoughts that created those feelings. Could you help?
I am getting better with processing my feelings, but when I have such a strong physical reaction I get overwhelmed and a bit scared. The physical discomfort intensifies in front of other people. When I am alone, I can process the feelings without pushing them away or buffering. But when I know, that I only have limited time alone or am with other people I struggle to process my feelings and push them away. Iā€™d love some help navigating this. Thank you!