Thank you for asking you query at DoctorSpring,
Although white patches and rashes can occur in HIV they are NOT usually the presenting symptoms (usually occurs late in the disease) or technically NOT AIDS defining illness. This means they are not specific of HIV (Please note, I am referring to the rashes you have described. Certain lesion as in Candidiasis can occur in HIV-AIDS initially ). Also the fact that you have no other symptoms makes it less likely that the rashes are due to AIDS.
However, you do have some amount risk of contracting HIV due to the risky sexual behaviour in past. So it is safe and advisable for you to undergo an HIV testing. And that is the only way to know for sure. You can go for a simple HIV Antibody test which is widely available. Most possibly the results will be negative, but just to be sure you need to do it. There is a home based test called Oraquick . I would not generally recommend this test as the results are not very good. You can go for it only if you do not have access to healthcare resources otherwise.
Remember to use condoms and try to stay away from risky sexual practices.
Please feel free to ask follow-up questions.