Intertrigo Caused By Tarceva?

Hi everyone - my mom's been on Tarceva for 4 months now. During the first 3 months she had minimal rash but on the start of the 4th month she developed a skin disease called "intertrigo" and it's mostly at the "fold" area of the body (i.e. under the breast, under the knee, etc...)

Her oncologist didn't think it's related to Tarceva, and her dermatologist told us that it's probably caused by her weak immune system.

So I guess my question is: Is Intertrigo somehow related to the use of Tarceva? The itch/pain of the skin are so unbearable for mom right now. Any help/info on this will be greatly appreciated. Thanks in advance everyone.

My husband has been on Tarceva 150mg since end of may.
He also had bad rash.
He started taking Benadryll (25mg) every night ( makes you sleepy so don't take in the morning) and the rash went away.
I noticed that when he was getting chemo one of the drugs administered was benadryll so I felt safe and asked the oncologist.
He said that in the beginning of chemo they look for the rash to see if the tarceva is working. But once that is confirmed then go ahead and start the benadryll.
Hope this helps.