When playing rummy can you pick a card up from the deck, and before laying it down call a rummy on yourself?

if thats the last card you have, you cant discard it because its an automatic rummy on the table so you just call rummy on yourself before laying the card Cefixime down right. You dont let anybody see the card, you just call pharmacy whithout prescription rummy on yourself and continue on right. You cant discard a rummy it doesnt go to your other players you can call it before you discard if thats the only play you have left right.