What Causes Red Blistering Lumps On Face, Neck, Chest And Back?

for the past two weeks i have been developing very red, angry looking blistering lumps on my face, neck, chest and my back. They only seem to come up when I am at work. Every morning I go in and the lumps are still there but only slightly show. As the day goes on they get worse and I can feel my skin burn, my eye lids burn as does the roof or my mouth. On a few occassions my throat has felt tight as though I am getting tonsilitus. I have been to the doctors and have been told to stay off work for at least a week but I am worried that as soon as I go back it will all happen again. I have been given a steroid injection and have to take 12 tablets a day (6 steroids, 5 piriton and 1 cetrizine tablet). I have worked there for over 8 years and love my job very much but we have recently moved into a brand new building.... I am not drinking water at school nor eating anything different so how will I find out the cause of my problem?