hi welcome to healthcare magic
From the above history it does not look like a normal allergy
as you have been put on steroids
and antihistamines .for any allergy there has to be an allergen which you are allergic to ,only you should find out what is that one thing that is causing these symptoms .you can get this allergy testing done ,liver function done ,total count ,IgE levels and please dont discontinue prednisolone
suddenly .take one tab zentel
400mg at night .
take care thank you