Poor Lexie! I hope her tummy is feeling better!
I think that perhaps you should go back to the original brand of pill. Maybe this one is either too hard on her tummy, or possibly there could be some ingredient in there that just does not sit well with her. I am quite sure that was the reason why she ate the blade of grass, to soothe her tummy, by getting rid of what was bothering her. I would figure that she has spit up most of the medication, if not all of it.
When I had to give Sammy his meds, I used the Pounce kitty treats, because at the end of them, there is a little "pocket" you can make by squeezing the ends together. I would do that, then just put the pill inside, then squeeze it back together.
He just loves those treats, so he'd gobble them right up.
Maybe Lexie will love them too!
Hope you feel better Lexie! Nose kisses & ear scritchies