Well, if you have any doubts that your gecko may be sick; for one I would make a vet appointment, and for two, bring a fecal sample with you. It may be that your gecko's fresh 'poo' just happens to have a green tinge to it do to the vitamins the crickets/meal worms are fed, or if you feed your crickets greens to gut load them.
As far as breeding your gecko this season-- I would personally wait till the gecko is older or till a proper breeding age. Unless you know the age/breeding history of the gecko his/herself.
Cheers,
Cat
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0.1.0 African Fat Tail
0.1.0 Leopard Gecko
1.1.0 Cats
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2.2.1 Platy's out the wazoo
2.2.0 Lemon Tetras
0.0.1 Pleco
1.1.0 South American Water Frog
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1.0.0 Husband