Did you change the seat post height the corresponding amount you changed the crank length (ie, did you drop the seat around 2-1/2 millimetres? It doesn't sound like much, but it can make a difference to fit and feel and leverage.
Are you riding more hills than previously? Or have you increased your intensity on rides? Sometimes the quad muscles need a certain time to acclimatise to extra effort, and until then, are more likely to cramp.
One of the things you might consider doing is to use a salt-substitute that reduces the amount of sodium chloride, and replaces it with potassium chloride. It might be on the supermarket shelves as Lite Salt. Potassium is useful in cell function. Lite Salt also is stronger in taste than normal salt, so less should be put on food that normal.