Seems like you had a recent prolonged sun exposure leading to sunburns over the exposed sites..
So firstly, i would advise you to use a sunscreen regularly from now before going out in the sun,,,,
Use a sunscreen with atleast 26 spf and apply it on all the exposed areas.
You should also re-apply the sunscreen every 3-4 hours in case of prolonged sun exposure...
And now, for the rashes that you have developed, apply a mild steroid
cream like mometasone
cream over the affected areas twice a day for 4-5 days,,and you can take antihistamines regularly for itching...
Next time be careful before stepping out in the sun ...wear full sleeved clothes ,wear a cap/hat if possible for sun protection
Hope it helps
Dr Geetika Paul