I don't think is chamomile is allowed as it is a flower ( i think anyway). Mint is allowed and I have started drining Dr. Stuart's Detox tea I know this is not a detox but I bought it ages ago, didn't try it until now but tried to yesterday and it was delish. The taste is non-existant when you first sip it but the after-taste is delish, very minty.
You can also drink earl grey, green tea, any leaf tea. No flower teas or fruit teas because of the sugars that might take you out of ketosis.