Hi Hun,
Aww injections are nasty! I just googled it for you and heres a link that might be useful,
https://www.babycenter.com.au/baby/health/fever/
I think its fine, just keep an eye on him, especially after his history, Im sure he'll be fine, keep us up to date.
Take care hun, xx
did your health visitor give you any advice about calpol?
a high temp is a common side effect