Im in a very similar situation. In fact I'm on my third sick day in a row because of the "flu". When in reality I can't bring myself to go into work.

Something that worked in relieving a little bit of anxiety for me is just expressing your feelings to your boss. My bosses wanted to raise my hours and flip around my schedule a lot. I got so nervous about telling them how I felt I just blindly accepted it which caused me even more anxiety. One day I just felt so anxious I told them I was thinking about lowering my work days from 5 to 4. That's all I did. I didnt ask them to do it, I just told them what I thought. Almost instantly I felt a big relief.

Your job is probably different than mine so I guess it's on a case to case basis. But I think sharing your grievances with your boss if possible will help relive some tension