Holiday with sun allergy

[L1974]

Hello going on holiday on Sunday should be looking forward to it but I have developed a sun allergy in the last couple of months and dreading in case I break out in a rash and end up poorly. My problem hasn’t been diagnosed as yet it’s following the solar urticaria pattern but without itching! I’ve got a 6 year old to entertain so it’s gonna be hard to stay out of the sun! Am taking strong prescription antihistamines and using factor 30 but within minutes my skin reacts. I’ve always been able to tan so this is really odd and I’m 44!? Any advice from fellow sufferers greatly appreciated.