Really struggling

I am so sorry to post again, I just don't know where to turn to help myself in my situation. I have previously mentioned that I have started a course part-time and some volunteer work.

I am three weeks in on the course and two weeks in volunteering. The course is a struggle. It involves a lot of practical work with working in two or threes. A lot of focus on what the other s saying and having a response. It is something I wanted to work towards career wise, but wonder if it is a little too far to reach. I have had some people think it is a good idea to do the course and others who think it is bad choice. So at the moment I am doing it day by day, but feel concerned that I will one day quit.

The volunteering as I mentioned is with children. There are two of us and the other person leads the session, so does all the explaining of tasks and summarising what they are learning. From day one I have struggled to interact with the children. It may seem silly, but I find even the smallest interaction is difficult. For example a child may say their leg hurts. I just don't know what to say, yet the other volunteer is so natural and may ask "oh I am sorry, do you know why it hurts". There are all of these small interactions, my mind is just blank. If the children are doing a physical activity. The other volunteer may give small instructions "keep head facing straight ahead" or "well done you are doing great". None of this comes to mind. Very rarely I may be able to say "you are doing well", but it is very rare. I just find it so difficult. I mentioned briefly to the lead volunteer that I struggle to know what to say and when to say things. That I was stressing out. They were great about it and said I was doing good and that I should just be myself. That if I need prior information on what the next session is then she can let me know etc.

I thought it would help, but I have just come from a session and I feel awful. It has been a huge shock struggling so badly. Now I feel deflated and feel I am just going along to make numbers up. That I am not really volunteering because I am not joining in. It is horrible to feel this way. 

I don't know what else I can do. The thing is if I stop the course and the volunteer work it will have a bad effect on my mood and I know I am just holding it together now. Not sure who to turn to because those closest to me already expect me to quit and I cannot mention my struggles. I have often been told that if I don't change my life will always be this way. 

It has taken so much for me to even study and volunteer. I am just scared that if I can't maintain it my mental health will suffer. I just don't know what my options are. I mean obviously I am hearing the interactions between the lead volunteer and the children. I can see how the interactions work, but I cannot do it myself. I feel like a loser who can't even hold a conversation.

I am really sorry for posting again.