I have been on IV Zithromax for a little more than 2 months I to switched off of rocephin which I was doing really well on but, I was having gall bladder attacks. I don't want to break your spirits because this is just my case but I have gone backwards since the change... I am not a huge fan but there aren't many IV choices. Zithromax helps a lot of Lymies so maybe it will be the key to your treatment. I hope it is