It does look like a Fe'ish kind of deficiency to me which is pretty uncommon outside of over-fertilizing or having a way-high soil pH so addressing a Fe deficiency isn't usually as straight forward as say, something like a nitrogen deficiency. Have you been fertilizing at all or have you just been giving water?
Do you have hard water? If you've been using water only, been in the same pot for awhile, and your water is hard/alkaline, that might be something to consider as far as something that could be raising the ph of your soil (if your soil's pH is wack). Either way, an up-pot into a good fresh potting soil would probably do the trick.
That's just my opinion anyways. :) Good luck man! I'm sure you'll figure it out.