On Thursday 13th May i got prescribed with Retin- A gel 0.025% to apply to my chest and back to treat acne. Before i was prescribed this i used Retin-A gel 0.001%

I apply the gel every evening and I am seeing improvements in my acne but on Monday i noticed a sore, red blotchy area on my chest, which looked quite like a burn. I never had this with the 0.001% gel. What should i do?

Also, I'm going on holiday soon where i will be highly exposed to the sun and i it cannot be avoided. Should i stop using the Retin A gel whilst i'm away? Or continue using it with plenty of suncream? If i stop using it for that week will my skin reverse back to how it used to be?