OP, I’ve suffered from migraines for 20 years and I’ve had it all in the headache stakes - a few that looked like strokes (hemiplegic, I think?), a few from aseptic meningitis (which isn’t dangerous but the headache is HORRIFIC), and then now the last few months, I’ve had daily headaches again (not had that since I was 17).
The rule of thumb for A&E for headaches, from a neurologist, is “first or worst.” So if it’s the first time you’ve ever had the type of headache happen or it’s the worst it’s ever been, you should be going to A&E if you can. So last night, you would have been completely justified going to the A&E and they wouldn’t have “told you off” or something. Headaches that have started causing night sweats and vomiting can be very serious, and they need to see you when it’s happening, if possible.
Second, and this is COMPLETELY out of left field, but you might have a small leak of spinal fluid? It causes headaches like what you’re describing and in particular, the headaches will: feel worse when you bend over and feel worse when you lay down. The “feeling worse when you lay down” is an important symptom. You may feel better after 12+ of sleep or in the morning because that’s when your body has had a chance to “replenish” and then it slowly leaks all day. Some people experience a runny nose with this, BUT some don’t at all as it goes down their throats, so they might have a slight sore throat, or if it’s a small enough leak, maybe you wouldn’t feel it at all.
The wait list will probably be horrible but at this point it sounds like you need a head CT and an appointment with a neurologist.
My other bit of advice would be next time you have a headache, before it’s unbearable (if this is possible) or you feel too nauseous, DO try to actually get some caffeine in you. Some flat Coke (just pour it in a glass and then stir it to make it flat) or some tea. See if the caffeine helps with the headache at all. For some people, it’s a headache trigger, but for others, it’s a big help with headaches when they’re happening.