Im I bracing wrong during exercise ?

Sometime for no reason I was doing heavy bench press and I ask for help with a weight that I knew that I would fail but the person would helped me to lift it , I felted that I almost passes out ( I didn't) when I got up from the bench I had a almost like a big rash on one side of my neck and some red on my cheeks and on the sides of my face ,it took 2 weeks for it to go away but now everytime I go for a pr or just a heavy training it appears everytime and on the same places , a few weeks ago I went to a championship on bench press there I almost again passed out but now I got another type of rash on the other side of my neck but this type is just some circles spread on the side of my neck.

It does not itch , it's not a lump ,the areas doesn't became sensitive

I'm I bracing wrong and that's why is appearing this things or is it another thing ? Anything helps.