Scientist would be the way to go. First Aid and Medicine are Professional Skills and, as Allen pointed out, one of the Scientist's Professional Development packages is "Medical Doctor".
I had that in mind when I recently made a medical officer NPC for my series. He's a more mature Vulcan (89 years old), who was an accomplished Vulcan Healer prior to the Dominion War, when he volunteered for Starfleet to provide his medical services where they were needed. On the sheet, I listed his Profession as "Scientist (Starship Medical Officer)".
Former Decipher RPG Net Rep
"Doug, at the keyboard, his fingers bleeding" (with thanks to Moriarti)
In D&D3E, Abyssal is not the language of evil vacuum cleaners.