Is it permissible to offer expiation for an oath, given the difficulty in fulfilling it, knowing that the oath involves bathing with water and lote leaves and reciting Surat Al-Baqarah after Fajr prayer with the intention of seeking healing from intrusive thoughts (waswas)?

We advise the questioner to fear Allah and abandon these whispers (waswas). A person overwhelmed by waswas, losing control of their will, is not bound by an oath.

If, at the time of taking the oath, you were overwhelmed by waswas, then there is nothing upon you.

However, if the oath was taken by your own choice: if you swore to do something, you are obliged to fulfill the oath or pay expiation. You have broken your oath by ceasing what you swore to continue doing. Therefore, expiation is incumbent upon you, and the oath is dissolved by your breaking it.