Ring the doctors back in the morning before 10am, tell them you want an appointment that day and if they say they haven't got any then state that you require a home visit, then see how quickly they find you an appointment.

I had a really bad kidney/urine infection about 2 years ago, but I didn't get any pain behind my nipples I just had horrific shooting pains across my back and then when I got the infection in my blood I had shooting pains down both legs, not the best 2 weeks of my life, but I did lose a stone