Thanks for your question. The most common reason for a foreskin rash would be a yeast infection or fungal rash and this will clear quickly with application of an antifungal cream like clotrimazole.  If this was the type of cream that you used and your rash cleared, then this would confirm a fungal rash. Herpes does not clear with an antifungal cream. If you are unsure about this, you can check with the doctor who prescribed it for you.
Herpes blood tests are not done routinely as an STI test as most people have been exposed to herpes ( estimated 8 out of 10) and will have a positive result. Herpes is easily transmitted through contact like kissing, sharing drinks, contact sports like rugby or wrestling and oral, vaginal and anal sex. The herpes blood test does not tell you where the herpes is on your body. HSV type one prefers around the mouth but also can be on the genitals. HSV type 2 prefers to be around the genitals but can be on the mouth.
It is possible to pay for herpes blood testing and typing in British Columbia and you could talk to the doctor about paying for the test. Usually it costs around $130 to do the HSV typing test.
If you have symptoms again, it is best to see someone while you have them so testing can be done if needed. Hope this helps. Health Nurse