Is the ablution of one who suffers from urinary and fecal incontinence sufficient if he performs ablution once upon waking, knowing that he is unable to reach water to the bottom of his feet due to muscle spasms? And is it permissible for him to shorten and combine prayers during his travel for treatment, which may last three months, given that he misses the 'Asr prayer daily due to the treatment?

If you suffer from urinary and fecal incontinence, you must perform ablution (wudu) for each prayer after its time has begun, and pray with this ablution both obligatory (fard) and supererogatory (nawafil) prayers until the time for that prayer ends. This is the view of the majority of scholars.

As for past prayers, you are not required to repeat them, especially if your ablution was not invalidated by an impurity other than the continuous discharge, because some scholars are of the opinion that continuous impurity does not invalidate ablution. Furthermore, ignorance of some conditions and pillars of prayer exempts one from repeating them according to many scholars.

If you are unable to wash some of the limbs for ablution, then perform tayammum (dry ablution) for the limb you are unable to wash.

Regarding shortening prayers (qasr) during travel, you are not permitted to do so as long as you will be staying for four days or more, as your ruling is that of a resident. However, you are permitted to combine prayers (jam') due to the excuse of illness, according to many scholars.