Hi!
I can contribute one of 3 characters--or all three if you'd like! ;)
First off, there's
Saffron who could be one of the medics. However, I'm thinking that her role in the guild would be as a side job, since she does have her own guild to manage called "Healing Wings." Her duties there could overlap with this guild since she travels to wherever needed. And she would have a personal understanding with mages too, since she herself underwent ridicule and supervision due to her own talents when she used to live in Connloath. So I offer her up as a potential member.
Secondly, there's
Citrine who could do any sort of mercenary tasks asked of him, provided it isn't morally questionable. Plus he has the added benefit of being able to teleport directly back and forth due to his Shadow Walk ability. Perhaps a messenger/agent could inform him of The Clinic, maybe your Lynette character and it goes on from there? Citrine's part would be an agent.
Thirdly and lastly, there's
Ray. Now here's the deal on him. Since he has a magic shop located in Darken Vei, your witch doctor would need to come to him and not the other way around. It would be too inconvenient and risky for Ray to travel to Connloath, especially with the civil war going on there. But if these terms are okay, then he could serve as a sort of agent/associate of the guild. But if not, that's okay too.
In order of convenience, Citrine is the most convenient in terms of actually getting there and leaving without attracting any sort of unwanted attention, then next is Saffron, then lastly Ray. Let me know which ones of these will work for you.