A pharmacist can't write a new prescription, but I know that my local pharmacist noticed that I was on the wrong type of anti-inflammatory for my condition, got in touch with the GP herself, and next time the prescription had been changed.
A well-qualified pharmacist probably knows as much as, or more, about how certain medications work either separately or in conjunction with other drugs, however to discuss your condition properly you do need to see a doctor, and you should not have been refused an appointment.
Good luck.