On top of having a picky eater I have a screamer too!!

So yesterday while in Trader Joe's Luka starts to scream. I walked into the store (have never been there before) stop to look at something and he starts scream, like this that's really what he looked like. He proceeded to do this on and off for 10 the lenght of time I was in the store. I was mortified and it was high pitched scream too and that store is small. An older woman asked me if I get a headache at the end of the day from the screaming . I did try to ignore it and he didn't stop. Then I took him out of the cart to hold him and he still did it. We then went to Waldbaums and he only did it twice there and I felt like I really needed to entertain while before I would give him toys and talk to him and that was enough. Now I am so nervous to go to stores because I do not know how to stop this. He isn't even cring just opens his mouth nice and wide and screams like someone is attacking him.

Any suggestions from BTDT moms?