Doctor for non residents

Hi, please can anyone advise?  We have a holiday Casa by Albanchez and use it 90 days here, 90 days UK etc.  We currently have a visitor staying for three weeks and she has been badly bitten by mosquitos and the bites have turned septic.  We called in to see the chemist in Almanzora and he was very helpful advising us to take her to the doctor thinking that she should have an injection.  He kindly gave us the details of the health centre in Albanchez. We called in this morning and following a long wait (although there was no one in the surgery). The doctor said that she needed to be registered and may have to go to Albox but to wait further.  We told him that she was here for a holiday only and not a resident and that she was expecting to pay for any treatment.   He said that she still needed to be registered. We had a further wait (doctors instruction) until a nurse arrived and she told us the same thing.    No consultation took place, her bites were not looked at and we had been there for almost two hours.  

1.  Can anyone please explain the procedure to me and explain why she needs to do this?

2. Fortunately, my partner and I have not needed any medical advice ourselves but are now thinking that we should probably do the same. Both our visitor and us have travel insurance.

Thanks in anticipation.