I haven't personally dealt with this, so I'm just offering my generic opinion. What is the active ingredient in the cream, is it anti-inflammatory, anti-microbial, something else?
In terms of how to deal with what I'm assuming is the problem relates bacterial or fungal growth on a moist part of the skin. I would try to keep the area clean, dry, and try to treat flare-ups with something anti-microbial. The 2 products I'd be looking at are iodine and chlorhexidine. Iodine is still one of the best products we have in terms of cleaning a sore, it has a distinct advantage over many alternatives because it doesn't damage the skin, the major drawback is of course pain. And since Toby is unlikely to understand that you are trying to help him, I'd probably not choose this option. Chlohexidine is another option that I particularly like. I used to actually own a mint flavored version (from the pet section at wal-mart) that was intended for cleaning teeth, it isn't painful to apply like iodine is, but still gives good broadspectrum action. It's not a food, but if he swallows some it's no big deal. Most versions I see available are liquid, but if you want a gel version of chlorhexidine KY jelly is a good non-toxic option. You can apply using a cotton ball or q-tip depending on the size of the area affected. Personally I never use petroleum based ointments for sores (like neosporin), because they create an environment that can allow the growth of anaerobic bacteria.
Once this bout is settled, you'll probably have better results doing a little bit frequently to prevent problems, instead of waiting till the problem is bad and then trying to fix it.