Botanist expertise needed: Unknown leaves?

Backstory: I had a small amount of leaves given to me as a gift from a friend. She had spent some time with some native peoples in Guatemala and one of the villagers gave her these leaves as a gift, and told her they were good for muscle aches. They were collected from the forest floor. They are light greyish-green with a reddish tint. Neither she nor I know what they are, and the man who gave them to her didn’t tell her the name.

So, she gave me some and instructed me on how to use them. You put a small handful into a cupful of boiled water, and steep until the water turns reddish. You then remove the leaves and pour the cupful into a full warm bath, and soak. It helps relieve muscle and joint pain. I tried it after a day of lifting boxes - it really works!
One characteristic/caution about it is that it really dehydrates you, so you have to drink a lot of water on the day of usage to avoid adverse effects.

Sorry for the lack of details, but I really know nothing about it and would like to find out more. Does anyone have any theories/possible answers as to what these leaves may be?

Here is a photo of a couple, if that’s of any help. They don’t smell musty like leaves on the forest floor would. They smell slightly sweet, not a bad smell really. The dry leaves begin to feel warm if you hold them in a moist palm.

http://smg.photobucket.com/albums/v654/MachTurtle/?action=view&current=DSCF0605.jpg

It may be Ginkgo Biloba. It does grow in Guatemala according to the web search.

http://reflexstock.com/index.cfm?/imageDetails_en&imgid=1679820&extIntCode=0

I have no idea beyond that.

Definitely not Ginkgo - The leaves are larger, a bit reddish, and shaped differently. I know this is a real shot in the dark. I’ll try to see if I can get some more info from my friend.

Those leaves don’t have Ginko’s parallel venation.

Ooookay, got some clarification. Either she told me wrong or I got it mixed up, because they’re not from Guatemala, they’re from the Amazon Basin, and apparently they’re called Tweepie - she doesn’t know if that’s the way it’s actually spelled, but that’s how it sounds. That’s a bit more to go on, anyway.

Bump.

I still haven’t had any luck finding info on what the English name for these leaves would be. Google searches produce only odd results that don’t resemble the subject at all.