I'm sorry you're having a setback. Here are a few things that I've learned:
1. Stay in the present. Forget about the past and the "what ifs" of the future. What are you doing, or not doing now? What are you planning, or not planning now?
2. Stay in uncertainty. OCD wants you to get on its treadmill and ruminate all day to find out, absolutely, that whatever's bothering you is not true. Sorry, ain't no such thing because we can't see the future; but, guess what, neither can OCD!
3. Imagine that you're a mouse on a treadmill. OCD wants you to stay on that treadmill. You don't want to be on the treadmill, which is why you want to stay in the present and stay in uncertainty.
When I get one these flare ups, (and yes, we OCD Conquerors get them, too, sometimes...) I'll say to myself: " I accept the uncertainty that I'll ever do (whatever it is) because I don't know the future, but I'm not doing it now, I'm not plotting on doing it and I have a choice." I then think about that mouse on the treadmill and resolve to not go there, even if I have to sit in discomfort for awhile, because I know it will eventually pass. And speaking of which, I've learned that it's okay to sit in discomfort because it actually makes me stronger. If I'm sitting there and not giving into compulsions, either mental or otherwise, I'm taking away OCD perceived power.
4. Don't try to block the intrusive thoughts and feelings, because they're just thoughts. Go ahead and let them in and then move on. The more you face them, the less severe they'll be until they no longer bother you much or dissipate all together. It's called habituation. In fact, you want to challenge OCD. You want to think: "Bring it on, sucker, because you'll always lose. What do you have, OCD? What else you have? WHERE'S YOUR VALID DATA TO BACK IT UP?" And guess what, OCD has no valid data, just it's twisted opinion. Hope this helps.