I have sore tender breasts lower back pain and a metallic taste in my mouth we are trying for baby but have only been trying for 3 weeks any ideas ?

Back pain, taste: What meds or hormones are you on? Have you had a pregnancy test? This could be related to pregnancy or hormone changes.

Need more info: Your age & GYN history would help me to give you an answer. The three major complaints you mention can be the harbinger of something not good or the effects of being pregnant,. I would strongly suggest that you make an appointment with your obstetrician very soon.