toddler rash caused by sunscreen and sun exposure? moms please help?

it looks alot like solar utacaria, and what ive read ppl ca develop sun sensitivity by certain chemicals in sun screen. i put sun screen on my little one and she went out tide and came in after an hour and had a slight red rash where i had put her sun block on(spf 70) it continued to flare and her skin got red and splotchy . strated to itch at heck and now its itching ll over. I used the walgreens brand of baby sunblock spf 70, its not expired. the only other factor was she took -similasan cold and mucus relief(100 natural remedy for 2 yrs and up ) actice ingredients *homeopatic* antimonium sulphuratum, ,kali iodatum, senga officinalis. yes ive called the dr and the overnight nurse told me 1/2 t benadryl and cool bath which i did. she has been able to sleep just wakes up fussing and itching and i get her to stop and go back to sleep. shes not scrathing real bad but i worry when she wakes up she will be scratching more. seems a little bit better this morning after two rounds of benadryl in the last 12 hrs. what do yall think?