Re cracked heels. I have had great success with the following -
Before you put your feet in any liquids use an emery board to remove any dry flaky skin. Your feet MUST be dry for this. Wet skin will only move with the emery board not fall away. The type of emery board is important. Here we use the black style. The types for nails that come in different colors i.e. pink blue etc. The reason you don't want to use the metal ones or the one designed specifically for the feet that are like cheese graters is that they are too hard and pull too much skin at once from what is already a very dry area. Think of how they would leave the cheese looking. I always recommend that this can be done while watching the telly or listening to the radio cos you can't damage yourself with these as you can with the metal type. Try to get the hard bit on the edge of the cracks without making yourself sore. You will be very surprised at the amount of dust that you will see coming away from your skin but this is normal. The brown old fashioned emery boards are too gentle and the black ones are perfect. When the dust stops flying move to the next part. If you are getting sore at all you have done enough for the day. More will come off tomorrow.
Rinse that dust off your feet as while it is blocking your pores you will absorb nothing transdermally. And it should only be dust, if you see larger bits of skin the emery board is too strong for you. At this stage you can soak your feet in any liquid of your choice i.e. anti-fungal, vinegar, peroxide or oils or salts for as long as suits you. Doing this with a couple of sports clubs some of the men chose to do it with plain old washing up liquid (detergent). So it is a case of whatever suits you. Use antiseptics or peroxide if there is any chance of an infection or dirt being caught in the cracks as it may close over the dirt and cause a diferent problem.
Then this is most important. Pack the cracks with some kind of thick oil. Our choice at the time we did this was vaseline but some would not choose this because of the petrolatum issue. Whatever you use press it over the crack to ensure that it has gone in the full depth. These cracks cannot heal while they are dry. If you had an operation on your stomach and the skin dried out to the same extent it would not heal either. We usually put large medical issue bandages over them to keep the vaseline on the feet.This won't suit everyone so a cotton pair of socks will do. The people we did this with all had to walk home so bandages were needed to keep the vaeline well packed. Wash next day as normal and leave bandage off. You want your feet fairly dry to repeat the process the next evening.
Remember it will be easy to slip on the floor until this is washed off. Do the same the next evening and continue til necessary tapering the amount of times done as they heal.
This worked within 3 days for some and some took approx 2 weeks. But it makes sense that the hard skin needs to go and the skin to be wet for the cracks to knit together.
As for the fungal infection. Many people will only treat the area that they can see the infection on. The human eye cannot see all of a fungal infection so if it spreading nor can they see it when it is at the last stages of treatment so it is very important to treat outside the area and for a lot longer that you can see it or feel it. My husband picks up an athletes foot while he is travelling for business on a regular basis. He never feels it but we can see it between his toes. We only know he has it when I catch it because I get the itching and burning long before I can see it. We use a providone iodine antiseptic wash which is normally used for pre-operation swabs in a footbath then antifungal medicated creams. Because he gets the moccassin type we bathe and cream his feet up to the ankles. I only get the moccassin type around the toe area so I only need to cover the shoe area. This is a long winded way of telling you how to do it but it actually doesn't take long perform it. The longest part of it is how long you choose to soak you feet and it is our tried and tested method.