Rashes are a pain, sorry you’re experiencing that right now. Symptoms like rashes are not used for diagnosing HIV or other sexually transmitted and blood-borne infections (STBBIs), because they can be caused by other infections or factors like soap or insects that you have already mentioned.
The only way to know if you have an STBBI or HIV is to get tested. Because you are sexually active, we’d encourage you to ask your health care provider for STBBI testing. You can also discuss treating this rash with them.
In the meantime, we recommend using safer sex tools like condoms and lube until you know your STBBI status.