@Cate64,
It might just be that your onc only prescribed a certain number of injections at a time, like with other medications. I am not sure how these things work but I would be thinking that was a possibility. That might have been the last one under that prescription. When you see your onc this Friday he/she will review your situation and if things are going well (which you have every reason to think they are from how you are feeling) then you will probably just continue with your current treatment.
Keep busy and let us know how you go on Friday. I will have my fingers crossed that it will be all good and no changes for you. You are doing so well with all your running! Try not to stress (I know, easier said than done!) Sending hugs and keeping my fingers crossed for you. Deanne xxx