What is the ruling of Islamic law if I fall and suffer harm, knowing that I suffer from excess electrical activity in the brain and may suddenly faint, and the doctor has forbidden me from working in high places, but I am forced to do so?

A doctor's advice not to work in high places falls under taking safety precautions and protecting oneself from danger, which is a legitimate objective and one of the five necessities [of Islamic law]. If it is highly probable that one will faint or be harmed in high places, then working in them is forbidden, because high probability in such cases is treated as certainty. Precaution must be taken, and if another job is available that does not expose one to danger, then one should switch to it. However, if no other job is available, then one must weigh the probable harm of fainting against the certain harm of losing money, and in that case, one is not required to leave the job.