What I don't get is what I do with this presciption medicine I take that comes in a 4oz bottle if I remember correctly. It's a schedule 3 controlled substance sold by only one pharmacy in the whole country. Taking it in any container but the original would be suspect since it's also a known street drug.

Medical liquids can be brought through in any necessary quantity. Sai (link: http://s.ai/tsa/ ) tried this with juice but found that agents were not particularly willing to play nicely since juice doesn't seem like a medical liquid...whatever that means. I expect that yours should be a bit more obvious. In theory.

There's good information there. Thank you.

3.38 oz = 100 mL. Lots of toiletries come in 100 mL containers.