Hello Ruby1967 and thanks for posting, 

Things like this can be a worry for any mother, but in general, because cancer is rare in children, when symptoms like this crop up, common explanations, for example infections, are much more likely.  So it would probably be a good idea to give the antibiotics a go and see if the lump starts to clear up and if not,  get back in touch with the surgery. 

I don't know if anything will change as a result of the photo, but if you feel your son needs to be seen, then be persistent and ask for an appointment with the GP. If this doesn't work think about contacting the practice manager and asking them to help.

I hope this is of some use, call us if you want to talk anything over on 0808 800 4040- we are here weekdays, 9-5. 

Best wishes,

Julia