Hi Bigred,
Check out the practitioners page on this website for a start. Another thing that you can try is printing out some information on CH's from this or the Headaches Australia website and taking it along with you to your GP. If they still don't take you seriously you may need to be a bit more demanding and ask for a referral to a specialist.
CH's generally only last about 90 mins but you can have a few in one day. You mention your headaches last from a few days to a week which is more typical of migranes or some other cause, in any case wise to get them checked out.
One of the best things to do to help your GP/specialist is keep an accurate diary of each headache i.e. date, time, symptoms, intensity, any medications, when you took them and did they work etc. You can use the CH Diary on this website or alternatively there is a good one on the
www.nps.org.au website - search "headache diary" that you can print out.
Cheers,
Bruce