#1---"is it possible to have blisters in your genital area and it NOT be caused by genital herpes?"
Certainly, it's possible to have blisters in your genital area and it is not caused by genital herpes. There are other causes of blisters besides herpes e.g. some people are allergic to the sweat that is secreted in their genital area during sex and they break out in tiny red blisters. Cholinergic urticaria patients are sometimes allergic to their own sweat.
Irritation from friction during intercourse can cause erythema and sometimes blisters.
When the penis and the female's genitalia are involved then Candida albicans is likely. Candidal infection of the penis is more common among uncircumcised than circumcised men and may result from sexual intercourse with an infected partner. Most candida infections can be treated at home with over the counter or prescription medication e.g. Femizole-7, Gyne-Lotrimin, Monistat, nystatin, or oral Diflucan and amphotericin B.
#2---"is it possible that I passed a rash and not herpes?"
It's not possible for you to pass your allergy rash to your partner; however, it's unlikely that you passed the herpes virus to your partner so soon after having sex. An allergy is an immune reaction to an antigen (a foreign protein). Antigens that trigger allergies are called allergens. One of the symptoms of an allergy is a rash that occurs when the skin is in contact with an allergen e.g. in your case latex since most condoms are made of latex rubber. A contact allergy rash usually occurs 6 to 48 hours after using the condom. Symptoms of herpes usually occur from 2 days to 3 weeks after exposure to the herpes virus.
"had sex with my partner with no condom. about 2-3 days after we had sex, she broke out with similar syptoms a bit more severe than mine (cluster of blisters, etc)."
This sounds like it may be herpes ("cluster of blisters"). I suggest that you both have a herpes culture and a HerpeSelect antibody test.
Since you said that you get the rash only after you use a condom then that means that you don't have a rash when you don't use a condom. This is not a symptom of herpes. Herpes appear whether or not you use a condom.
Let me ask you a few questions so I can be more helpful. Did you or your partner feel a sensation like a shooting pain or a tingling sensation in your groin? What did your rash look like and what does your partner's rash look like (be very descriptive)? Did the rash consist of clear fluid-filled blisters that looked like tear-drops? Do the blisters itch or tingle? Did the blisters open-up, drain a clear or slightly milky-colored fluid, and then form an ulcer that looked like a depression where the blister used to be? Did you have any swollen inguinal lymph nodes (glands between your legs up by your hips that felt like frozen peas)? Did your partner feel any swollen lymph nodes? Did she have a clear or slightly white vaginal discharge?
Herpes 1 can be spread to the genitalia. You or she may have been shedding herpes 1 viruses and infected each other. Herpes 1 is common; most people have antibodies to herpes 1 by the time they're 10 years old.
The only way to know for sure is to have the fresh lesions cultured and have a serum antibody test (HerpeSelect).
Close-up of a typical Herpes cluster of vesicles.
It's possible your "irritation" is a herpes break-out because you mention that it is ALWAYS in the same spot on the left base where the condom meets the penis. A herpes virus can be inoculated through the skin by skin to skin contact. From oral-genital contact (herpes types 1 and type2) and from genital to genital contact (also herpes types 1 and type 2). Although, herpes 1 is usually found in the labial area (lips/face) and type 2 is usually found in the genitals. However, this is not always the case. And, as I said previously, herpes type 1 is common in most people.
At the place where the virus is inoculated, the herpes virus DNA attaches to part of the person's DNA and forms a capsule around itself and then it moves on down the person's nerve to replicate (clone) itself within another part of the person's cells and so on along the nerve to the nerve ganglion root and sometimes all the way to the person's spinal nerve root. Then the herpes virus remains dormant (not replicating) until for some reason it will become active and the person will shed particles of the viral DNA. The person might not know they've been infected because they may not have any symptoms. The virus can sometimes cause paresthesias which can include "anesthesia" which means the person won't feel the painful blisters. Sometimes when the virus recurs (recurrent herpes infection) the virus will move along the nerve from the root back to where it was originally inoculated and then it causes the skin lesions which are usually itchy and painful.
Your partner's blisters sound like a cluster of herpes vesicles (see photo above). There are some people who don't have as severe a reaction as other people; however, usually they will feel "itching" or "tingling" sensations which is due to the herpes virus irritating the nerve.
I suggest you both be tested for herpes by having the HerpeSelect and if you have a blister with fluid then have the fluid cultured immediately because there is a chance of a false negative culture the longer the blister is present (over 48 hours). Fresh herpes blisters are usually positive for herpes. Since your girlfriend has fresh blisters now, then this is the ideal time for her to have the blister fluid cultured.
You both should have the HerpeSelect test which may come back negative with low titer levels but that just means that you should wait another 4 weeks and be re-tested. Sometimes, if a person is newly-infected with herpes, they will have a low titer level for IgG and/or IgM antibodies because their body hasn't had sufficient time to build-up an antibody response to their infection. It doesn't mean they're not infected with herpes---just that sufficient time hasn't passed for antibodies to be formed and therefore be picked-up by the HerpeSelect test.
If you have other questions please ask me.
Dr. Hanson, MD, PhD