From the description it seems, you are having acute urticaria
In most of the cases no underlying cause can be found, however infection, worm infestation, drug or certain foods can precipitate its occurrence.
The treatment is anti histaminics that you are already taking. Kindly continue with montecip- LC for a week or so then discontinue it to see if the rashes still occur. If they do, continue it for another two weeks and consult a dermatologist
Hope that helps.