It could be really similar. You usually see it with inland lakes when there is a lot of duck and goose poop. It's some kind of bacteria that basically causes you to get a rash and itch. Most people I know take a shower right away after they swim in an inland lake. Just to be safe.
https://www.mayoclinic.org/diseases-conditions/swimmers-itch/symptoms-causes/syc-20355043
poo poo can be dangerous! I never would have guessed that this was the underlying cause. Sea lice is actually very small plankton-sized creatures that have stinging mechanisms similar to a jellyfish. It's kind of shocking when you go through a swarm the first couple of times because you can't even see them and you tend to go face-first when scuba-diving.
Oh gosh, that sounds horrible. I was always freaked out by jelly fish when I was a kid. I was afraid I was going to get stung by one no matter what type of water I was in!