Thanks for asking your question here.
There are many reasons for having a rash
, viral infection etc. If you feel that your baby is running temperature, please record it with thermometer and consult your doctor again.
may have felt that the rash is related to J&J soaps.
Allergy can be from anything including the clothes/chemicals/food etc. Soaps have many chemicals.
My advise would be to try different brand baby soap (without perfume & hypoallergic soaps) and see if the rash re-appears or not. There is no particular brand of soap which doesn't lead to allergy. So, it is basically trial and error to find out what suits your baby's skin.
Most of the times it resolves very quickly.
Dr Tejas Shah