Very worrying for you sherrardk.
Can I just clarify the history. Six days ago he felt something pop in his head - did the headache come on after that, and was he doing anything strenuous like lifting or straining at the time? How long did the weakness in his arm last for?
Four days later he had some speech difficulty which has now resolved, but the headache is ongoing.
If that is correct, then he does need another medical opinion and full neurological investigation including MRI.
Could you not persuade him to register with a GP and be seen - they will sometimes do this on the same day if pushed.
If his headache gets worse, or he develops any other symptoms, I would take him to the A&E department of your nearest large hospital rather than back to the walk-in centre.