Can I Take Allegra Once Daily While Breastfeeding To Treat Itchy Red Rashes, Since Avil Is Unavailable?

I am suffering from red rashes around my hands , face , stomach and legs with itchness from 4 days and also i am having 2 months old new born baby and i am breast feeding too i treated with applying caladryl lotion on affected itchness area and intake okacet tab for 2 times a day even though i am not cure as doc suggest me to take avil for two times a day but avil tab has stop supply in almost all pharmacy instead of avil shall i take allegra 120 mg once a day after meal.so pls suggest me the right one doctor.