Didnt know cleaner shrimp could be physically sick??

[Blag It]

Hope someone can help, I've had my fire shrimp, cleaner shrimp, and hermit crab in the same tank for weeks now. All was going well. I do water changes weekly cuz it's a small tank, and I keep an eye on all the necessary levels. Nothing has gone wrong or been changed since I got them, including their three different foods. Does anyone have any idea why today my cleaner shrimp has started to shake quite hard sometimes and is being literally sick?? Never seen it before, nothing comes up on google :/
Any help would be much appreciated!!

[melosu58]

Could be that it is getting ready to molt. a shedding of the outer skin to put it broadly.