Dr Timothy Johnston Pediatric Dentist, North Fremantle, 9433 6082 (no referral needed)
Dr Ian Gollow, Pediatric Surgeon, Subiaco, 9382 2627 (need a referral from GP)
Dr Liz Whan, Pediatric Surgeon, subiaco, 9382 2627 (need a referral from GP)

ETA - many Lactation consultants would also be able to diagnose and refer you on. You can check out the LCANZ website for someone in Perth.