you aren't pathetic at all dumburn. It's really hard to be assertive sometimes.
If it helps, i dont think that you have to actually ask your GP if you can see someone else. You would just call the reception and ask if you can have an appointment with another GP. Maybe tell them your pain problem and ask if there is anyone who specialises in (or has an interest in) pain management. See them for a time or 2, and then if you feel that they are helpful you can request to change GPs to them.

Good Luck