When I first start teaching full-time, I kept getting what I called "Heart Palpitations". It felt like my heart would do little flips over and over again. The doctors had me where a heart monitor for 24 hours and then told me it was stress and that I need to calm down.
They also gave me a prescription for something to help calm my nerves but since I really don't like to take pharmaceuticals, I just learned to deal with it using deep breathing. It also helped to vent my frustrations to my husband when I got home. He very patiently listened to my rants without trying to fix things for me. It seemed like once I got it "off my chest" the stress decreased.
So, in other words, Lilac, don't hold it in. Just vent here and maybe that will help.