What should a person do who sought divine guidance (istikharah) and then embarked on the path for which guidance was sought, but found no comfort in it and encountered continuous problems: should he continue on it, or switch to another path?

After performing Istikhara, the servant should proceed with the matter, and whatever outcome it leads to is the result of the Istikhara and is good for him. If he is diverted from it by any kind of deterrent, then that is the good, as Ibn Uthaymeen said. And if obstacles and problems recur, and your heart turns away from the matter and you no longer desire it, then this is an indication that abandoning it is better for you, and there is no blame in that.