Something like a blood oath, when performed, is meant to be a serious undertaking. They are difficult to back out of because the purpose of such a working is to literally swear, on your blood, that you will recognize and honor some sort of an agreement or pact. the whole point is that swearing something on blood is to declare it as something you will treat as unbreakable.
Now, of course there's not a magical force that can -make- you perform that oath, it is essentially little different than making a promise, and a matter of personal honor. But choosing to break that promise also has the normal consequences you would expect. IE; the person or entity you made the oath with getting upset that you are going back on your word.
To best understand the situation, and offer ways to fix it, we would need to know as much detail as you can give about the working. Was it in a formal ritual setting? Was the oath between yourself and another person or yourself and another entity/being/deity? What -exactly- was the wording of the entirety of the oath? What was the purpose of the oath? What were you trying to gain from making it/what was your goal? While making the oath what promises were made, and were any consequences declared if the oath should be broken? This can all be very important information.
If you are lucky, you might be able to stop this curse through a formal apology and perhaps some sort of offering of appeasement. Most often this sort of situation is like committing to a debt. As long as you pay your debt in some way that is accepted by both parties, the problem might go away.
if the oath was around something more complex, then it could require more work to solve.