I suffer from erythema despite having sunscreen, what should i do?

Hi, every year in the first sun even with 50+ cream I get a strong erythema on my face, arms and neck. After the erythema has passed, I can generally sunbathe safely without further problems. The point is, I only have 2 weeks of vacation and I don’t want to spend one at home. This year the dermatologist recommended HELIOCARE ULTRA D from a month before the exposure until the end of the ester and carovit melanin 1 week before the exposure and during. How about? Thank you