I can relate to you and you do not sound silly at all.
Mine started 13 years ago, I had many things happen in a space of a few months one of which was a car accident, very minor, I was in a traffic jam and got hit from behind.
A week or so later my mum was having to take me to work and I got stuck in a traffic jam again, my stomach started churning and I desparately needed to toilet I ended up having to go behind a bush since then I have been afraid of the feeling of being out of control, not been able to get were I want to starts my stomach off again, it has prevented me from doing many a journey, I travel at night on motorways so I have very little risk of feeling trapped.
This went on for a long time, 4 years ago I had to start walking the kids to school and thought, how do I get there, there is not a toilet in between and I can't use the school ones, will I get back on time, I used to get into a right pickle about it. I then heard that peppermint helps you relax, so I bought some stong mints and because physcologically (sp?) I was told they would help, they did, (sounds daft I know), everyday I would leave home armed with my mints and they became my safety source, and now somehow, somewhere along the line I don't feel bad anymore, I don't know what has happended to change it, maybe I have become more confident. I am also aware the a few of my friends have felt the same at some point, which helps because I bet a % of people in the playground feel the same way too.
Even sometimes now, if I am gong on a long journey with friends who don't know/understand I reach for the diacalm, but its not very often.
Just wanted you to know how I dealt with it, daft as it seems, maybe worth a try, but of course if you are finding it incredibly hard to cope with then a trip to your GP is the right thing to do. HTH Take care