Is it permissible for someone afflicted with OCD to go for Umrah despite their fear of obsessive thoughts there, and would their undertaking of this be considered a struggle (jihad) against the obsession?

Our advice is that you continue to strive against yourself and proceed on the path of treatment for this waswasa (whispering), knowing that Allah will help you get rid of it. You must take the initiative to go to Allah's Sacred Land and turn away from the satanic waswasa, for you will not be held accountable for it. Strive in supplication there, asking Allah to grant you complete well-being, and drink plenty of Zamzam water with the intention of healing.