Getting my 4mo baby to take a bottle?

I have been breastfeeding my daughter since the day she was born. We used to try & give her a bottle but we stopped trying for the fear of nipple confusion and engorgement. I hated skipping feedings because it hurt my chest. Now, I am having troubles with back and shoulder pain.. I went to see my Dr. and he said I have alot of muscle spasum in my shoulders and back.. And feeding my DD all the time is making this pain much worse.. I would love to have her take a bottle sometimes until I can get this pain under control, but she just dosn't want anything to do with it.. I was thinking of trying out the 'breastflow' bottle.. But i'd hate to buy such an expensive bottle for it to never be used... I'm stuck and not sure what to do... I will not stop breastfeeding her, my goal is 1 year and I don't want to stop, id rather deal with the pain then stop... but any suggestions on how to warm her up to a bottle now and then?