Mum has cramps & diarrhea for 1 week now, dad had some diarrhea, i have cramps gas and slight nausea but no diarrhea or anything. would i have gastro?

Same virus: You most likely have all infected each other with a contagious agent - perhaps norovirus or one of those epidemic viruses. Every person reacts a little differently to disease -depending on their underlying health, their genetic make up (immune system), youth etc. I would say you have a gastroenteritis -sure. Best to rest, drink fluids/salt-chicken soup, rice, simple foods. AND try to avoid others.