Welcome to healthcare magic forum
Thank you for your query.
I understand your concern regarding your skin problem
I am dr Gaurav patel ,dermatologist
and will answer your query.
answer 1- Yes ,rash
could be symptom of salmonella
2- there might high chance of getting it from swimming .It may come from infected food also.
I hope I answered your question.
Let me know if you have any further query.