Diaper rash since 2 weeks.pls help

Hi,

My son is 5 months old and he has Ben having a very bad diaper rash since 2 weeks now. He is been weened of breast milk recently, after he got the rash thought. The rash is red and gets dry at times, doesn't look like it hurts him, but gets irritated at times when I'm applying any cream, I tried calendula but that made the rash every red and dry. So stopped using it, doc gave him derma dew with aloe, it seemed to help a ill but he got the rash again.

From the past 4 days he been spitting up some milk like curd and smells bad. Once immediately after his feed and at times after some time.

I Hv stopped using the diapers during the day so it seems to be better but I use the diapers in the night as its getting cold out here in Hyderabad. I didn't want him to cach cold.

Apart from the diaper rash he has red patches on the arm folds, neck folds too, which again is getting better n comes back after few days.

I'm not sure as to what kind of a rash this is, if it's any way a yeast diaper rash.

Please advise as to what should be the best remedy. It's been 2 weeks now I'm really worried if it could spread or get worst.

Thank you!