I wouldn't give a suppository, if she's refusing to take something orally I doubt she'd like something being inserted inside her against her will. If she does happen to respond well to a suppository, and you want to make it yourself, I'd use coconut oil, as it's antibacterial and antifungal. But I would go to a compounding pharmacist personally.

Have you tried what Nai's mum did? Crush up the medication and mix it with sweetened condensed milk? Set it in a little shape, and then it's like a lolly. You could put sprinkles or something on top. Or, crush it into juice or other food?