When someone talks to me out of no where in public it takes me a while to register it because I'm so focused on being insanely anxious. Because of that, by the time I understand that I'm being talked too, it becomes too late to respond and I just end up being awkwardly silent. I wish there was a way to tell them that I am not trying to be mean, I just have a hard time talking to people out of the blue. Everytime this happens to me I just want to go to my dorm and never leave it ever again. God I feel awful. :(
So sorry you suffer from social anxiety. Do you have any idea why you suffer from this?
You could try certain SSRI medications that can help with social phobia. Paxil worked wonders for me when I suffered with this many years ago. I think for me drug use was my cause. I spent a good year partying in my early twenties taking ecstasy most weekends and it was towards the end of that year where my social anxiety kicked in. Quitting drugs and taking Paxil for around 6 months made the world of difference, then I quit Paxil and was perfectly fine again. It just goes to show that any disturbance to chemicals in you brain can cause havoc in many ways.
I know friends who are on Sertraline and they are so much more relaxed, composed and at ease in social situations compared to not been on Sertraline.
It's a fight or flight response and I think now it's in your head your also probably overthinking it, so as soon as someone starts talking to you, you think about your social anxiety.
Seriously, life is too short to worry what others think, so be kind to yourself, try to relax, focus on what they are saying and respond accordingly. Truly being present in the moment and really engaging with people will help.
Wishing you all the best.