Blurry Vision and Sore Body: Is it Stress?

Yes I get blurry vision and I will also get tunnel vision and if it's too bad I black out /pass out! I try and talk to myself when it happens and tell myself that it's okay and I am okay and that it will pass.. I am not always so good at telling myself all the time or believing myself all the time.. but it's easier now to do that then when I first started .. I tell myself it's gunna be okay as a way to try and calm myself