Where did you purchase the shrimp? I fed a piece of shrimp to my condy that I had bought at Kroger, and it had a very bad reaction to it. It blew up like someone had put an airhose inside it, and it never fully recovered.
Later, Kroger put up a label at the seafood counter that their shrimp contains sodium bi-something (sulfate, phosphate, can't remember now). I wondered if that was the problem.
Condy's often emit their waste shortly after eating in other words they will get really shrivled up for a few hours then get larger, mine does this every couple of weeks. another reason condys might behave this way is a sign that the bulbs in your lamp need to be replaced. hope this helps.
I will also put you at ease by telling you that it is normal behaviour. Anemones contract to expel waste water and soon after refill with fresh oxygenated water.
But I will also caution that feeding frozen/fresh-fish/shrimp/squid for human consumption are normally loaded with preservatives consisting of nitrates and phosphates,as well as iodized salt.