Many find that antibiotics can stall out weight loss – I think just the stressed state your body is in from whatever is causing the need for the antibiotics then the drugs themselves makes it hard to be in a diet like hCG at the same time. Many find it’s best to abort a round early if this happens and start again once you’re off it.
I would suggest you finish the antibiotics before taking hCG. I think that would also be beneficial because some antibiotics cause stomach pain when you didn’t eat enough food before taking it so if you’re on hCG you can’t really eat much and that can cause some extra struggle for you.