Suggest Treatment For Itchy Blisters On Skin

I have been on holiday and whilst in the sun my skin started to itch. Then the next day my arms have been covered in itcy blisters. i was using factor 50 and have not been burnt. These blisters are full of clear fluid. and they vary from small ones on there own to clusters that have all joined. Have you any idea what i can do to clear them. I have been using an antihistamine and a hydracortisone cream with no avail .