The hot tub you relaxed in obviously needs cleaning. Your bodies are having a reaction to the dirty bacteria ridden water of the hottub you were in. Your pores are absorb a lot, and if the water was very dirty then it can cause your lymph nodes to swell --since your lymphatic system is one of the defenses your body has to clear out impurities. The same goes for cosmetics, soaps and deodorants. Caking on the deodorant or not rinsing soaps well can eventually cause reactions with the body--seeing that most store bought soaps and deodorants contain many chemicals. Using natural products and soaps help, but your most important defense is to be active and eat healthy.
The mini trampoline is a great tool to keep your heart strong, keep your lymphatic system working and help your body work like it should. Our bodies are designed to filter out all this junk, but when we are sedentary or when we overwhelm our bodies with chemicals or foreign products like scented soaps and deodorants our bodies eventually get sick and have a reaction.
It could be almost anything from overexposure to lawn chemicals, household cleaners, laundry detergents, scents, bacteria in water or food, etc. Evaluate yourselves and what you eat, apply to your skin or come in contact with and try cutting it out.