For an act to be wrong, even before it to be sinful, one of the factors we have to consider is whether the person is free to act otherwise. More simply speaking, for me to commit a wrong, I need to be physically and morally free to do so first.
An example of physical impossibility is sickness. If I am sick to the point of not able to go to Mass, then it is right for me not to go. In fact, it would be wrong for me to go.
An example of moral impossibility would be the need to look after someone else, and there are no viable options left for me to be free to go to mass. I could go, but I would be irresponsible for those dependent on my care. I should arrange for someone to help, but sometimes help is not available. My moral obligation toward those in need supersedes.
Another example of moral impossibility would be if I carry a contagious disease. My moral duty to avoid crowds would preclude me from going to the Church.
So, in your situation, one should attempt to get help. But when it is not possible, it cannot be a sin. It is not even wrong.