Allergic-type skin reaction when sick

Patient: This is not a typical allergy case I was living in an old house when I got a flu and an itchy skin reaction with it. I went to see a doctor, but I was calmed down and given some antihistamines. I was single with no relationships at at the time (for a few years before this). However, this has stuck so for the past 10-15years whenever I get sick, I get the same skin reaction. It’s worse, if I’m really sick so from the reaction I can always deduce how sever the flu etc is. I was around 25 when it started. Over the years the basic labs have been taken several times for other reasons, but nothing out-of-ordinary has turned up. However, now I’m getting a bit worried what’s going on, since the same happened to my husband a few months ago when he had a common flu, but he has had the skin reaction only once (and we have never lived together in the house when it started with me, although he did stay some nights there (we met like 1-1,5years later after I got the reaction the first time). We’ve been together over 7 years now, so it took years and years before he got the skin reaction the first (and so far the only) time. We are not trying to have a kid, so for most of the time (and for the last 4 years) we’ve used condom. What on earth this can be?

Symptoms: Symptoms: whenever I get sick – a flu, a stomach bacteria i.e. whenever my white blood cells are activated I get an itchy skin rash at the beginning of the sickness (fades away pretty rapidly, in a few days). It begins from the neck and upper chest with a few patches in the back. If the illness is more sever, the rash is more widespread to the thighs, more in the back, stomach etc.