If she laid her first egg, then it could be something reproductive. It won’t hurt to check for the presence of another egg that is stuck or too large to pass. Sometimes new layers will have problems or possibly have a shell-less egg that is hard to pass.
The symptoms of coccidiosis are sleepiness, hunched or puffed up posture, weakness, not eating, and runny poops, sometimes with blood. Amprollium or Corid (in the US) is a good treatment. It is very safe, and it goes in the water. Are you in the US? In some countries, sulfa antibiotics are used more, and amprollium may be called Toxoid or other names.