I would read the article that @azygous posted, she wrote it and it's very good
With holding them upside down and emptying there is a risk of them aspirating, so that's something I personally try to avoid doing.
Do you have coconut oil? I like that better since you can chill it then break it into small pieces. Mine usually will eat that very well.
Her crop is full and squishy so if I would not massage it - see if the coconut oil helps get things moving. The crop is just really a pouch that holds food/water but it plays an important part of the digestive system - it can turn boggy and sour if there is a problem with the process. An impacted gizzard or some inflammation somewhere in the body (usually reproductive system) can slow things down as well.
Is she able to poop at all?
For the TUMS, I would crush it or break into small pieces, sprinkle it over some food like bits of scrambled egg. TUMS does not dissolve in water, I tried that one time and it makes a floating powdery mess LOL
