It sounds like the vet did what I would have done. Do you have the receipt - it may say exactly what was given?
Sounds like he had pain meds at the time (probably something like Metacam by injection) and then a course of antibiotics to stave off any infection. 5 days is pretty much minimum course - any less and there is little point. As for dosage - if you can tell us (a) Si's weight and (b) if the Baytril is diluted or not (should say on the bottle if it is) then we can work out if the dosage is correct. It sounds about right to me though.
I agree with your vet that he doesn't need to go back unless he's not better or gets worse - if he gets better then there's no need to stress him out with another trip.
I don't know if it's been mentioned because this thread is quite long now - but probiotics are a good idea whilst he's on Baytril and for a short while after. I use AviPro Plus which is available online here
http://www.noahs-cupboard.co.uk with fairly prompt delivery, or your vet might stock it.