Muscle tightness causing increased anxiety

I thought I was getting my anxiety under control again, my doctor adjusted my fluextine from 40mg to 60mg, I have been noticing a good change, the last couple nights I have been having bad muscle tension in my back all around to my shoulder and pectoral muscle, upon that starting I feel as if I can't breathe, and my doctor can't find anything wrong with my lungs, can anxiety really be causing this problem or something else

Yes it can

I'm always problems in these areas

Makes me feel better that I'm not alone, how do you relieve the tension