This is not an unusual occurance. When you get a massage there is pressure exerted on your muscles, blood vessels and lymphatic system. That pressure cause the fluids within and between the cells to be released an a higher rate than if you were doing nothing. Those fluids often contain waste materials, which at times may also contain germs. As athey get pushed out and released into the blood stream, it can cause a person to feel sick. This is especially true if your body is already fighting off something. This mostly happens during a first massage or if it has been a long time between massage sessions. Also, most people are slightly dehydrated most of the time. Make sure to drink a nice big glass of water after your massage, this will help to flushout those toxins even quicker and you will feel great!