Somewhat afraid to go out with friends

A friend took me to lunch today. While we were conversing, my thumb suddenly came out of its socket. I could do nothing but try not to calls out and sit with my head bent, manipulating the joint until it went back in.

I am getting a bit timid about going out with someone for fear the thumb or shoulder will dislocate. It interrupts our conversation and my friend got very upset. These incidents are getting more frequent. How would you deal with this? I did explain to my friend and told her not to worry, but she was about to call the EMT's and get me to the hospital.