Retin-A sun damage early intervention. What can I do to reduce the effects?

Used tretinoin 0.025 microsphere since last month only 3 times a week nd stopped it 3 days prior to travel.forgot sunscreen and sunbathed for hours nd also lips got chapped nd lower lip red after it.also i already hypo pigmented skin patches on face from laser hair since last year .now read it can increase cancer risk as more sensitive .i am afraid so what can I do now to atleast reduce some effect at early stage. any treatment, creams or should I start retinoid again.trip happened 2 days back.