You are not in a particularly pretty situation, as there is no way that probation and the state will not learn of the new arrest. My experience is, however, that probation, unlike parole, will not violate you immediately. They will wait first to see the strength of the state's case.
Probation holds all of the cards with a violation, though, and they can be very difficult to second guess. They have a whole arsenal of possible sanctions available to them, ranging from a wrist slap (more intensive supervision, more reporting requirements, which is unlikely on a new felony) on the one extreme to house arrest or revoking probation outright on the other.
What they will do in your case will depend on many factors. If the underlying case was a diversion dispositon which would be dismissed at the end of your probation, that possibility is gone now, and the case will reopen. If you took another sort of plea, then it's going to come down to whether probation is still willing to work with you. If your underlying case was a misdemeanor, you might be able to get supervised probation on the felony, since it's a non-violent offense and have that cover the misdemeanor as well.
If the underlying case is also a felony, it will all depend on whether probation decides to wash their hands of you and revoke probation altogether. When they do that, they will usually make a recommendation to the judge about how much time they want you to do. Although the judge generally gives probation's opinion a great deal of deference, because probation has worked with a defendant far more closely than a judge, the judge is not bound by probation's decision. If probation is revoked, the judge has the power to resentence the defendant to any appropriate jail alternative defined by the state's sentencing law for the crime he originally pled to, up to the maximum the law allows. But they also have the power to restore you to probation even over probation's objection.
So there a lot of variables which presently I can only guess at. But you'll be entitled to a hearing, so if you already have one on your underlying case you need to contact him so that you have representation. That way if probation and the DA are asking for jail, someone can make a case for something less intensive, such as house arrest.