What should I do if I have a tailor's bunion?

Depends on severity. A tailor's bunion gets its name from the old time tailors who would sit crosslegged to sew. It's the bump at the joint where the little toe and metatarsal bone meet. If it doesn't hurt, just wear sensible shoes to avoid irritation. If it does, shoe changes, padding, ice, ibuprofen, etc can help. If pain persists, see a podiatrist to discuss surgical alternatives. It isn't hard to fix.
Many options. Treatment options for the management of tailor's bunions include conservative and surgical management. Conservative management options include use of orthotic devices, change in shoe wear, medications such as oral no-steroidal anti-inflammatory drugs (nsaids), steroid injections, padding of corns and calluses, and splinting and strapping.
It depends. Does it hurt? Is it difficult to wear shoes? Have you had any previous treatment? These are all questions your doctor will need you to answer before giving a recommendation or treatment.