There is no 24hr medical centres that I know of. However your closest bet is the Eltham Ridge Medical Centre which operates an after hours services through the week and on Sunday's. Be aware the visiting after hours will cost extra but I do not know how much, you will have to call to find out.
WEB:
https://www.ipn.com.au/gp/vic-eltham-eltham-ridge-medical-centre/home/Normal operating hours:
Monday - Friday - 8am - 6pm
Saturday - 8am - 12pm
Sunday - Closed
After hours:
Monday - Friday - 6pm - 11pm
Saturday - 12pm - 11pm
Sunday - 8am - 11pm
