ok .......my heart is not doing well

Ok ladies......I am in a panic......I am stage 3 bc......had 6 months chemo (CEF)...rads....tamoxifen......3 months of herceptin......after 12 weeks of herceptin......heart functioning has gone from 60 to 42........herceptin has been stopped and my heart will be tested again in 4 weeks......if it is not up to 55 I have one more month for my heart to come up to 55 to continue treatment.........after 8 weeks if my heart is not up to 55 the herceptin will not be continued! Has this happened to anyone? Have your heart tests improved? I so want herceptin....it is the closest thing I can get to cure me and I am so upset about this......Is this uncommon? My friend has the exact same thing happen to her........please post