I hope you have time to see your primary care doc before the trip - if it is erythema nodosum, you need to jump on it quickly with professional medical guidance. It may involve a punch biopsy, so you'll need more time.
I do find that anything I exert myself physically to do (yard work, walking, carrying groceries and laundry, old lady stretching videos) makes me inordinately sore. I usually retreat in alarm, frustration, dismay and shame and stop doing whatever it is that made me sore. Yeah, I know - thereby ensuring that the whole cycle gets worse . . .