Ibn Qudamah
It is permissible to skip fasting for a healthy person upon obvious risk, even if he has not fallen on the risk yet, and the author of Al-Mughni (Ibn Qudamah) stated in his book that some scholars even permitted skipping fast upon very light harm such as toothache or bruises on skin and if a traveling person is permitted to skip fast even if he is able to, then these type of "sickness" should be permitted. This position is said to be held by Bukhari, 'Ata and the Zahiris. However, this view might be considered as minority among Muslims, and it is unapplied since it may be used as a mere excuse for skipping fast.