needing reassurance

So my best friend has been on and off for 3 weeks her mum hasn't gotten anything which has been reassuring for me but we went on a night out on Saturday night didn't get back home till 8 am Sunday morning she was sick when we got back but only a little and just kept on dry heaving it is now Tuesday and she called me saying all night she was on the toilet throwing up bellyache fever headache you name it and I slept over saturday we shared drinks n everything now it's like I'm counting down the days it happens to me I am terrified but obviously we was out drinking Saturday so it does make sense why she threw up Sunday morning which doesn't bother me drunk sick does not bother me it's if she has a bug and now im terrified my anxiety is making me feel strange can someone please help