Holding breath

Hello. I suffer from anxiety I have GAD. Lately I'm feeling very stressed and anxious every day and it's affecting my daily life. There's just so much stress everywhere it's really horrible. I dread every day and my body aches and feels tight.

When I feel stressed out and the anxiety causes my body to feel like it's alight I've suddenly started holding my breath. I don't know why. It's almost like I get this feeling that says hold your breath and the anxiety can't touch you. It's weird but it does start to help, I feel my body start to calm itself and everything feels light almost like I'm starting to fly. But the problem is I start to feel unwell after a while and get a little dizzy. I realise I probably shouldn't do this but a bit like stabbing my arms with my nails it's a habit and I can't stop it.

I'm not going out at the moment but soon I'll have to with family and I'm worried that I'll hold my breath then and I'm not sure what to do about it. 

Any advice or tips are welcome.