Can I Just Stay In Bed?

Because for the last week or so, I seriously feel like crap. I'm not sick. I can teach a full day, although somewhat more irritably than usual. I feel up to going to the gym, though I only have about a half hour in me. I have an appetite. I don't have a cold or the flu. But I'm continuously nauseated, metal mouthy, headachy, tired, unfocused, PMSy and generally not right. So, can I curl up and hide for awhile?