It's possible it is related to Vitamin B or iron deficiency -- the pill form of B is poorly absorbed so try to increase it in foods. Don't eat salty foods while you have cracks in your mouth. There is plenty of iron in pumpkin and hemp seeds, you don't need a 10 lb. steak.
I had this for a week last year and it went away. I believe I was using coconut oil or pure aloe vera gel at the time.
Some people use lemon juice as a natural antiseptic, instead of antiseptic creams. There are other anti-fungal and anti-bacterial oils out there, so just try to find the most comfortable and affordable one for you.
And beware of the budget dish soap "cure for clown lips" -- it seems to just dry the lips more.