Hi small doubt did hiv test result negative after 28 days of risk attitude but after 10 days of test found 1 rash in my stomach ,any chances?

Not HIV: HIV doesn't cause rash alone; without sore throat, fever, and/or enlarged lymph nodes, you can be sure the rash isn't due to new HIV. Also, if you had a 4th generation or "duo" test, the negative result 28 days after the last possible exposure is conclusive. If an antibody-only test, it's still around 95% reliable, but for reassurance you might get tested again at 6-8 weeks. Good luck!