We need a photo of the poop that looks like yolk. I take it that the poop is yellow? Coconut oil won't turn poop yellow.
A little known, but not uncommon, phenomenon is two eggs, not a double yolk egg, coming down the tract in a single 25 hour cycle. This can spell trouble for the hen that has this issue. I had an EE that spent an entire spring before this recent one producing two eggs each cycle. There isn't usually enough calcium secreted by the shell gland for two such eggs, so one may be shell-less.
Shell-less eggs are more likely to get bound up, and they are more likely to collapse. I put my EE on a daily dose of people calcium, around 500mg, and kept her on it until she reset her cycle. It took over a month, but she began laying a single egg each cycle again, and this season, there has been no issue.
If there's a stuck egg or egg material from a collapsed egg, the hen will be trying to push it out. There may be a watery discharge from the vent, either clear or milky white. It will change color to yellow when the collapsed yolk is expelled. There can be a danger of vent prolapse if the hen is pushing hard for an extended period. Giving calcium can help.