Can’t get rid of this rash😣

My baby started with a rash on his face and eventually got it all over his body also. When I took him to his 2 month shots the doctor told me it could possibly be eczema but she said just to use either eucerin or aquaphor for babies I mentioned I had been usimg aveeno but didnt seem to be getting any better. My baby will be turning 4 months in a few weeks and the rash just gets worse and worse. I made a drs appt for him nxt week just want to know if anyone went through this with their baby and what you used on baby’s skin? Any suggestions?