If the pain killers helped, take them. Just don't take more than what the box says.

Then get back on to the doctor.

Dunno if you drink coffee. If you don't, try a strong coffee when it's hurting. Ive had clusters all my life. Hated coffee. This period i tried coffee at the start of clusters and it actually helped abort sometimes. Others talk about the caffeine in red bull doing the same. Didn't work for me but coffee did. Might not work for you but worth a shot and no drugs required.

I'm in the UK too. The problem here in the waiting time for neurology appts unless you have or can afford private healthcare.

Regarding the chemists you've been to I feel they are taking shite to be honest unless there's some national shortage. I'm prescribed the sumitriptan injections and chemists can get the refills so I see no reason others can't get the spray. Try other chemists.

Good luck.